Spells to protect my cart.

[The Vagabond]

Let's say I want to protect my little gyspy cart, which is also my home. It contains a ton of alchemical materials, and other various things. Assume half WBL, and able to cast spells as a Level 11 Wizard. What spells should I use to protect my little cart home from common thieves, and higher level opponents?

[Aergoth]

Breaking it down by spell level then, since you don't want to be spending your best defenses against

1st level

Hold Portal is a bit of a Hail Mary since it'd lock you inside if you can't get out via teleportation or similar.

Alarm is always a good first step, since it's 20 ft/level you've got 220 ft of warning. Ditto for Invisibility Alarm, which focuses specifically on creatures that are (you guessed it) invisible. Both of these can be made permanent with a casting of permanency.

Stumble gap on or around your doorstep isn't bad either, since it's a partial save that's still worth -1 on all rolls (including damage) and checks.

Even if you don't have allies, Keep Watch is a great spell to cover your back with, since it removes the need for sleep while still allowing you to prepare spells and so on.


2nd Level:

Arcane Lock: Like hold portal, subject to the same bypasses but equally useful since it doesn't lock you in.

Crimson Confession: Want to be able to tell who messed with your stuff? It's a permanent spell that will last half a day if the person doesn't have access to a caster.

Obscure Object: Security through Obscurity is obviously a good idea. You can ward objects of up to 1100 pounds with this, which may not be the weight of your entire cart empty, and it's only good for 8 hours.

Misdirection: As above, might be worth putting this on the contents of your caravan to keep people from going after choice targets immediately. It would also help hide some of the stuff to come from the unwary. Not for casting on the whole kit and kaboodle though.

Phantrom Trap: You only get one of these, so I'd put it somewhere that isn't important. Faking a trap to anyone might put them off things (probably won't). On the upside it's not a spell that grants anyone a save.

Sentry Skull: A little grisly but mounted with the right props your might get away with it. Primarily to serve as a backup to the alarm spells. Redundancy is lovely. Again this assumes you spend time

3rd Level:

Nondetection: Might get a little expensive to cast on the day-to-day and can't be made permanent, but there are no size or weight restrictions and you'd get half a day (or a night's rest at least) out of it.

Explosive Runes: This really doesn't have to be explained, right? Put it on a doormat or nail it to your door.

Campfire Wall: If you have a construct or a familiar that could understand keeping a fire lit, you've got a shell that would block line of sight at night and damage the unwary, keeping all the light on the inside. And presumably your cart fits inside a 40 ft. sphere. At 11th level, it could in theory go most of the day, but I imagine it's a little conspicuous in the daylight.

Illusory Script: If you don't mind putting this on something inside, the suggestion of "walk away from the cart until the suggestion ends and forget where the cart is" isn't a bad one. If you're vindictive, have them trigger a trap with the suggestion. As with non-detection, the day-to-day casting might get a little expensive.

4th level:
Secret Page: Again, the unwary might enjoy if you combined this with explosive runes or sepia snake sigil

Fire Trap: Pretty much as above! Put it on something fancy looking!

Detect Scrying: Does what it says.

Symbol of Laughter: Expensive and worth making permanent, since it's a save or potentially lose 11 rounds of actions and will remain active for 11 minutes after the fact. I recommend scribing it on the inside of a doorframe! This basically goes for any useful Symbol of X spell.

5th level:
Mage's Private Sanctum: Only one downside to making this permanent, and that's the soundproofing, make sure your alarms are mental ones in this case. The 30 foot cube of darkness is also a little conspicuous.

Mirage Arcana: Hide the caravan. It's 11 hours worth of hiding, so it might require two castings, or swap it out for campfire wall during the evening.

Symbol of Striking: Might not be able to make it permanent so holding off for a bit isn't a bad idea.

Symbol of Scrying: Similar problems to the symbol of striking in as far as permanency is concerned, but knowing who is getting into your stuff is a good idea. Especially if you can know before they get inside.

Symbol of Pain: As above!

6th level:
Guards and Wards: This is probably the best abjuration you can do. It's going to be a bit like triggering the magical security system from hell. If you're travelling with other carts, might as well ward all of them, make them pick and choose. Heck, splitting stuff between your cart and a decoy might not be a bad idea. My vote is for the suggestion effect or the stinking cloud.

Symbol of Sealing: trigger a wall of force to prevent entrance. You want to pair this with the next suggestion:

Hardening: This is going to increase the durability of a substance. If you could somehow line the walls with another substance without substantially increasing the weight, this is how you're up-armoring your cart to keep uppity druids and jerks with passwall from getting inside easily. This is going to require a few castings, but it can't hurt! And lead is also an easy foil to a lot of detect X. If you've got downtime, this is what you prepare and cast every morning. Cast it on your windows for kicks. You increase the hardness by 5 each time you cast this spell.

Contingency: You have to be alive to enjoy the spoils of keeping people out of your cart. This will help!

[LordOfCain]

Wall of stone around your cart with explosive runes carved on the wall. Would-be bandits look at the explosive runes when trying to climb the wall and BOOM!!! They go flying off.

[TheifofZ]

Aergoth pretty much covered the bases.
I'd also include bound summons, mind-controlled beasts, and undead servitors to patrol for me, but those would likely do little to deter foes that are truly determined to jump a small gypsy wagon.