When you use two feats that require to take an attack penalty that should not exceed your BAB, can the combined penalties of both feats exceed your BAB?
I would read the ruels as saying that you can as there is nothing about 'combined penelties' However I don't think the extra modifiers matter either
You can take CE because the penelty (5) does not exceed your BAB of 12
You can take PA for the same reason the penelty (8) does not exceed your BAB of 12
This however is an Errata question : In calculating these (and simillar) things should all modifiers be taken into account on a cumulative basis at the time the skill is used or are these requirments pre-requists ?
AS ever it's G.M.s call lets do a little example (without dice rolls)
Two borderers are having a fight,one knocks the other to the ground and he fails to get up, The guy n the ground is much easier to hitsince he has penelties to parry and cannot dodge so it makes sense to give him a mighty whack.
In dice rolling terms you may only need to get a ten-twelve to hit so you should gamble reducing your attack bonuses to get most damage...
Yes there is a chance he will manage to parry but it's low and you could get upto 3 chances without any second attacks as in ---
He uses his 'move' action to try to get up provoking an AoO if you hit he doesn't get up
He goes first an tries again to get up provoking a second AoO and again if you hit he fails to get up
Then you get your attack
A sesoned player might not reduce his BAB to low on the first two rolls so as to maintain the advantagous situation an AoO against a DC of 12 (say) with a +8mod means you need to roll 4 or more to hand out plenty of damage and keep the guy down.
Also I would feel it is fair to allow this because while you are going to do a Massive amount of damage the downside is that you suffer a huge penelty on your attack roll.