Use the 75/2 and crop.
At least you will be able to see what you are shooting and the 75/2 has none of the "brittle" bad manners of the 90/2 AA in strong sidelighted scenes. In fact, I haven't been able to find any flaws at all..., nor has anyone else, as far as I'm aware. Must learn to use mine more though...
BTW, I don't buy Rob's argument at all, as nice as those shots are. If anything, the 75/2 has a gentler OOF than the 90/2 AA, especially wide open or nearly wide open. The transition is more gentle to my eye.