How defensive can you get?

[Pbartender]

OA's adapted Tumble rules say that +15 ranks in tumble increase dodge bonuses yet again, to x2 their normal value (more than the x1.5 bonus provided by 5 ranks).

OA has stuff that makes it the pimpbook to end all pimpbooks.

so... using your plan... (character is hasted)
Full round action; Total Defense (+8 AC). Partial action; dismissed attack action to activate Fight Defensively (+4 AC) and Expertise -5 (+5 AC).

total of... +17 AC, all universally stacking dodge bonuses. pimpitude!

Plus, you're Hasted...
+4 haste bonus

Plus, you're a 12th level Halfling...
+1 size modifier
+6 Dexterity modifier (Dex = 22 or 23)

With Dodge...
+1 Dodge bonus vs a single opponent.

So, all in all, with nothing but a Haste spell, you could have an naked AC of 39 (against a single opponent).

Without Haste, it'd drop to 27.