Can You Make Wounds and Vigor Work in 5e?

[Parvum]

Here's the wounds and vigor system. (http://paizo.com/pathfinderRPG/prd/ultimateCombat/variants/woundsAndVigor.html)
I really like the wounds and vigor system. Taken over hit points in the older systems, it meant players were better able to recover through dime-a-dozen vigour points while still feeling fatigue and resource drain through tough-to-heal wounds. Dropping to your wounds was palpably bad, but didn't straight up knock anyone out of the fight immediately. It even helped me better anticipate NPC and monster actions- if the players charm an animal, it fights until it takes wound damage and then flees. The fickle henchman battle until they are out of vigour. The barbarian rages when he takes wound damage.
I also really like the way hit points (or, rather, losing hit points) works in 5e. Characters seem a lot tougher to kill, and I genuinely like that. I think adding death saving throws and removing negative hit points was a great idea.
So can they be combined?
I really hope so. Wounds/Vigour created a space in between tip-top condition and knocked unconscious through damage. I'd like to bring that into my games, and have people still fighting to participate even as they make the rolls that inch them closer to death. I don't have a lot of experience in 5th edition though, so my abstract grasp on what is a lot and a little is sketchy. I'd like some help pulling these two systems closer together and fine tuning the changes to be made.
So here's some thoughts I had.

Vigour points seem simple enough to translate, removing the Con bonus from hit points just like before. No change needed, really.
Before I tackle wounds themselves, there's an idea a friend gave me about critical hits. There are no critical hit multipliers in 5th, so instead a critical hit deals wound damage equal to the number of die rolled to make the attack (possibly extra if the weapon has the Heavy property).
Obviously this means that a lot of classes can deal way more wound damage with their critical hits. Again, I don't have a lot of 5e experience so I'm not sure how often players get massive exploding critical hits that can drop monsters at full wounds, or how many monsters have this effect on players. So if we use this then Wounds might not be as simple as double your Con modifier, certainly not if the Wound Threshold is still a thing. Maybe wounds could increase with your level, not as dramatically as vigour but still incrementally. Less realistic, but hopefully less frustrating and makes for more tense near death experiences.
Also there's what happens when you're at 0 wounds. Do you straight up die? If the rest of the system works right, it shouldn't take that much longer to chew through both wounds and vigour than going through all your hit points, so ideally you can have a similar system of death saving throws and death by excessive damage past 0. But hear me out while I run my mouth- I'd like something that allows players to act desperately, dying but able to affect the outcome of their situation. So we have a Wound Threshold again, and when passed the character is in mortal peril. They make one save immediately to avoid falling unconscious. If they make it they can continue to act, but must make death saving throws regardless, the results of which remain hovering over the character's head until they are over their Wound Threshold (even if they regain enough vigour to be considered 'safe' from normal damage). Maybe tie the saving throws to actions taken rather than rounds passed, letting traumatized characters draw out their deaths even when they aren't in the center of the action.
Other things can get tied into that wound threshold too, perhaps exhaustion levels for characters who can easily reacquire vigour but stay below the wound threshold.
Spending hit dice would, I think, work as vigour healing does already with a couple exceptions. You choose to spend a hit die on vigour or wounds, vigour works as normal (dX+Con) while spending a die on wounds only heals 1 wound point (maybe wounds equal to Con modifier?). A character proficient in Medicine or an Herbalism Kit can make an ability roll to allow one or more characters to regain wounds normally (dX+Con) during that rest, and any character can spend one use of a healer's kit on themselves to do the same. Characters spending hit dice at the end of a long rest gain wounds back this way as well, in addition to all of their vigour.
Maybe it would work better if both wounds and vigour came back with one hit die?

So... is there a way to make it work?

[Talamare]

So basically, your actual HP is heavily reduced but everyone gains a ton of THP?

[Talamare]

I would do it like this, Easiest way

Your HP is now Vigor, No actual changes done to HP calculations. Keeps it simple.

Everyone gains a secondary HP called Wounds equal to Max HD for class /2 + Con
This amount never goes up, unless your Con increases. Tough Feat also increases it by 2.

So, let's say a Sorcerer with 16 Con, or 9 Wounds
Any time he drops to 0, he loses a Wound
Any time he is critted, he loses a Wound
Any time he is loses Con, he loses a Wound
Any time he suffers starvation, he loses a Wound

Maybe a few other effects, w/e

You regain 1 Wound every Long Rest, As well as Greater Restoration can recover 1 Wound.

Actually, with this we might be able to replace the Exhaustion mechanic completely

[Parvum]

So basically, your actual HP is heavily reduced but everyone gains a ton of THP?

Your HP is split into two pools- a big one that comes back easily and protects your life juice, and your life juice that is supposed to be harder to take out and harder to get back. That's the idea at its most basic. There's an idea behind it about taking some of the abstract out of hit points, where vigour is the vague luck and pep and wounds are the actual blood leaving your body. I don't care as much about that as how it plays and feels to the players.

[Parvum]

I would do it like this, Easiest way

Your HP is now Vigor, No actual changes done to HP calculations. Keeps it simple.

Everyone gains a secondary HP called Wounds equal to Max HD for class /2 + Con
This amount never goes up, unless your Con increases. Tough Feat also increases it by 2.

So, let's say a Sorcerer with 16 Con, or 9 Wounds
Any time he drops to 0, he loses a Wound
Any time he is critted, he loses a Wound
Any time he is loses Con, he loses a Wound
Any time he suffers starvation, he loses a Wound

Maybe a few other effects, w/e

You regain 1 Wound every Long Rest, As well as Greater Restoration can recover 1 Wound.

Actually, with this we might be able to replace the Exhaustion mechanic completely

Interesting. I might tie it to exhaustion somehow, so that there is that in-between state of top physical health and death. And I'd throw in spending a hit die to regain 1 wound during rests, though maybe only during long rests. I assume that hitting 0 wounds means death, right? Are there still death saving throws at 0 hp? And does losing those kill you outright, or affect your wounds again? If you can die like normal, this is basically another access point for character death (no change if you replace/blend it with exhaustion though).
I do like how it keeps everything to a really small number that is just as durable at high levels. So a rogue with a +3 Con has 11 wounds, and needs to get critically hit 11 times before straight up dying. A barbarian has 15 wounds, needs that many crits before getting taken out. I like it.

[Talamare]

Interesting. I might tie it to exhaustion somehow, so that there is that in-between state of top physical health and death. And I'd throw in spending a hit die to regain 1 wound during rests, though maybe only during long rests. I assume that hitting 0 wounds means death, right? Are there still death saving throws at 0 hp? And does losing those kill you outright, or affect your wounds again? If you can die like normal, this is basically another access point for character death (no change if you replace/blend it with exhaustion though).
I do like how it keeps everything to a really small number that is just as durable at high levels. So a rogue with a +3 Con has 11 wounds, and needs to get critically hit 11 times before straight up dying. A barbarian has 15 wounds, needs that many crits before getting taken out. I like it.

I see wounds as more of a long term, his body couldn't handle it anymore
Death saving throws is more of an immediate 'He's bleeding out!' (so yea, still kills you)
Could even make it even more BRUTAL by saying every failed Death Saving Throw ALSO makes you lose ANOTHER wound

I think its probably not a great idea to encourage Lv1 dips for higher wounds. So just make it like... 5 + Con
and if you want to add a bit of complexity + 1 for Athlete/Resilient/Tough Feat + 2 for Durable Feat + 1 if your Race provides (+2 STR) + 1 if your Race provides (+2 CON)

As for Exhaustion, I would simplify it to it only having 1 level. If you gain Exhaustion a 2nd time, you lose a wound.
As far as the Exhaustion effect, I would probably keep it a little minor but I can't think of anything at the moment

[Parvum]

I'm looking for something with a bit more immediate impact- I prefer urban settings where the characters can go from terrible danger to complete safety in seconds, where they'll almost never die of exposure instead of trauma.
But mostly I want more space in between straight up death and perfectly fine, and a chance for dying characters to act. I also want a secondary number for "How Boned We Are" for the players to keep track of in most campaigns, but also something I can make private and abstract for a horror campaign. I heard of an idea where the GM keeps track of hit points and players know how wounded they are but not how many points of damage they can safely sustain. I like it, but not keeping track of bigger and bigger numbers as well as completely taking over all the healing and damage distribution. So making wounds and vigor means the players still have something to keep track of but I've got the vitals they can't see directly.

These were the two things I had in mind when I set this up:

Wounds

Every character has a pool of wound points representing the lethal physical damage they have taken, and without these a character is one breath away from death. You have a number of wounds equal to your maximum hit die plus your Constitution modifier. Unlike your hit points, this number does not change as you increase in level unless you increase it with a feat, special magic, or increase your Constitution modifier. For example, a fifth level barbarian with a Constitution modifier of +3 may have 50 hit points but only 15 wounds.
As long as you have hit points it is difficult (but not impossible) to damage your wounds directly. Your luck and vigor can run out, however, and then your wound total can start to drop rapidly. When you are reduced to 0 hit points and the damage does not kill you outright (see massive damage) you make an immediate Constitution saving throw, with a DC of (8 + the amount of damage remaining after you drop to 0 hit points). If you fail the save, you are unconscious and begin making death saving throws on your turn. A death saving throw is a d20 with no modifiers and a DC of 10. Once you have succeeded on three death saving throws, you are stable and do not need to make additional saves. On a natural 20, you regain 1 hit point and are no longer unconscious. Every death saving throw failure deals you 1 point of wound damage, and after three consecutive death saving throw failures you stop making death saving throws and immediately lose an amount of wounds equal to half your total at the end of each of your turns until you are stabilized, gain hit points, or die. These successes or failures need not be consecutive, keep track of both until you collect three of a kind.
If you take any form of damage while at 0 hit points that doesn’t kill you outright, you suffer a failed death saving throw. If the damage comes from a critical hit, you instead suffer two failures.

Remaining Conscious
If you succeed on your Constitution save to remain conscious, you can continue to act but still make death saving throws at the beginning of each of your turns. Once you have failed three death saving throws, you immediately fall unconscious (no save). If you fail a death saving throw while you are stable (such as by taking damage) you immediately begin making death saving throws again, and you must succeed on three new death saving throws to become stable.

Stabilizing a Creature
If a character cannot regain hit points the best way to save their life is to stabilize them. A stable creature no longer has to make death saving throws and (if not tended or harassed afterwards) gains 1 hit point after 1d4 hours. A creature with a Healer’s Kit can stabilize another creature (but not themself) by expending one of the kit’s uses. Failing that, a character can use an action and succeed on a DC 10 Wisdom (Medicine) check to stabilize a creature (including themself). A stable creature must continue making death saving throws if they take damage.

Knocking Creatures Out
When dropping a creature to 0 hit points, the attacker can choose to incapacitate their foe rather than kill them. In doing so, the creature drops to 0 hit points and is stable, though they must still make their Constitution saving throw to remain conscious. If they are still conscious the attacker can make another nonlethal attack to knock them out, forcing them to make a Constitution saving throw (DC 8 + total damage dealt) without damaging their wounds or forcing them to make death saving throws.

Damaging Wounds Directly
Whenever a creature is subject to a critical hit from an attack, they take 1 point of wound damage. If the weapon had the heavy or firearm property, they take 2 wound damage instead.
Some spells and effects target wounds instead of hit points, bypassing hit points entirely.
A creature that suffers exhaustion from exposure or starvation takes 1 point of wound damage.
The Inflict Wounds spell can deal wound damage directly, if the spellcaster chooses. The spell deals 1 wound damage, and if cast at higher levels deals an extra point of wound damage for every level after 1st. (Other harmful spells might deal wound damage at DM discretion)

Surviving at 0 Wounds
It’s possible for a creature to cling desperately to life through magic or sheer force of will, though it is physically taxing. A creature that is at 0 wounds but still has hit points remaining, even temporary hit points, is still alive and can ignore their grievous injuries, but they must make death saving throws at the beginning of their turn as if they were at 0 hit points. On a natural roll of 20 they regain 1 wound. On a failed saving throw they suffer one level of exhaustion. These saving throws do not end when the character collects three successes- they continue rolling until they are saved or die from exhaustion.

Regaining Wounds
Creatures heal naturally from wounds, unless an effect prevents them. After a long rest, characters can spend a hit die to recover one wound per point of Constitution modifier (minimum 1). Healing can be accelerated by characters with Healer’s Kits or the Medicine skill. A successful DC 10 Wisdom (Medicine check) allows one character to regain wounds by rolling the hit die spent and adding their Constitution modifier to the result, gaining that many wounds. For every 5 by which the check is exceeded, an additional character can gain this benefit. Each use of a healer’s kit gives one character the same benefit for that rest.
During a short rest, characters normally do not recover wounds. A successful Medicine check or use of a healer’s kit (as above) will allow a character to spend hit dice to regain wounds as if they had done a long rest (one wound point per point of Constitution modifier).
The Cure Wounds spell and certain other effects can heal wounds immediately. The caster chooses if they want to heal wounds or hit points. If they choose wounds, they do not roll the damage healed- the character heals 1 wound for every die that would have been rolled.
(As a rule of thumb, most spells that heal less than a d8 cannot heal wounds. Those that heal a static number typically heal 1 wound for every 10 hit points, though specifics are subject to DM discretion)
Any magical effect that allows characters to spend hit dice will allow them to regain a wound instead. Some effects might recover both at the same time, at DM’s discretion.

Multiclassing
As a characters attention drifts to or from physical pursuits, their health may suffer as a result. Your wound total can change as a result of multiclassing. When you have class levels of a different hit die than your original class or monster hit die in excess of half of your total class levels, your wounds change to match the hit die of the new class.
(This is a blunt solution, but I'm not that concerned- if my players want to mix classes oddly, I will encourage it if that results in interesting characters)