Ok, I made a lvl 40 character instead, using only monk levels now. Worked. This is what I ended up with
Additional info
Main weapon: Unarmed (I thought it would be creature?? Took the wrong weapon focus then.)
Attack bonus: 33/30/27/24
Attack1: 2-20+12 (Critical 20 / x2)
Fortitude 26
Reflex 19
Will 38
Base Attack: 31
Spell Resistance: 37
Immunities: Crit, Poison, Mindaffecting, Paralysis, Disease
Damage Resistance
And of course AC 45
What do you think?
Edit: I test played it against a few high level creatures. The only problem it had was dealing with high damage resitance / reduction. Perhaps it could have been overcome if I specialized in Unarmed instead, I can't tell.