Sneak Attack and Stealth and Concealment (again)

[P.F.]

So my ninja has a sneak attack, which is great when we can get flanking. Surprise might work too according to the game rules but it has literally never come up.

Now, my ninja typically uses a standard action to deploy a smokestick, which gives him the opportunity to hide, and breaks line of sight if he is on the other side of the AoE.

In my understanding of the rules, a character in the smoke has concealment, but if he is next to a monster outside the smoke area, that monster does not have concealment and is therefore eligible to receive precision damage.

My character thus moves into the smoke, breaking line of sight, then moves adjacent to the monster. I still have concealment, and thus do not have to break stealth and/or become "in plain sight."

Can I force a stealth/perception contest? If I win, is the monster then denied its Dexterity bonus? May I then sneak attack?

[The Grue]

Per the Stealth Playtest optional rules (http://paizo.com/paizo/blog/v5748dyo5lcml), a character that successfully hides using Stealth gains the Hidden condition, and is considered invisible to any characters not aware of them.

Of course said rules are unofficial, so check with your DM to see if he'll allow them. Which he should, because it makes combat more interesting. If your DM is strictly core then your ninja is stealthed, but his opponents retain their dex bonus to AC and are not vulnerable to sneak attack.