More than doable in multiple ways, especially with having such broad requirements.
R16/A8/NWN3/IB3
AB: 24 (BAB) + 10 (DEX) + 1 (WF) + 4 (EB) + 1 (EP) -2 (PTWF) = 38 AB without any buffs
Sneak attacks: 8d6 (rogue) + 4d6 (assassin) + 2d6 (NWN) = 14d6
Bodyguard/Neverwinter Nine for 3 levels is a no-brainer in any sneak attack build that can spare the class/levels since it is the only way to get full sneak progression and high BAB. There are other options as well...
R16/A9/IB5
AB: 23 (BAB) + 10 (DEX) + 1 (WF) + 4 (EB) + 1 (EP) -2 (PTWF) = 37
Sneak attacks: 8d6 (rogue) + 5d6 (assassin) = 13d6
This is (or was before epic shops) the Rogue build. The extra AC from INT/IB synergizes well with Assassin.
A couple less obvious options
R19/M3/A8
AB: 22 (BAB) + 10 (DEX) + 1 (EP) + 4 (EB) -2 (PTWF) -2 (FoB) = 33 Below your minimum. However, having 1 extra sneak attack out of stealth can be considered to make the loss of AB to be acceptable. Instead of 4 sneak attacks out of stealth you are getting 5 and 2 of them are at highest BAB instead of 1...
Obviously can gain +1 AB stopping R at 16 and taking 3 levels of Bodyguard, but then you won't have HiPS until level 30.
Sneak attacks: 10d6 (rogue) + 4d6 (assassin) = 14d6
As stated, instead of 4 sneak attacks out of HiPS you get 5 thanks to bugged extra attack from Flurry of Blows.
R16/A8/GFK3/NWN3
AB: 24 (BAB) + 10 (DEX) + 1 (EP) + 4 (EB) -2 (PTWF) = 37
sneak attacks: 8d6 (rogue) + 4d6 (assassin) + 1d6 (GFK) + 2d6 (NWN) = 15d6
All of these can have epic dodge, epic precision, expose weakness and PTWF.
I could give likely a half dozen additional flavors, but point is it's not such a hard feat to accomplish...
Good luck with it Winterborne!