Yes I could and I'm not timid about doing stuff like that. But, for me at least, that's not a solution. When I use BBF in press mode, I want a big, fat, protruding button that I can easily get to and press with any part of my thumb. Simple stick-on half beads give me protruding. But the thumb grip would have to go.
I specifically noted "Press" mode. If that's what the OP uses, he can decide if he wants to keep the AF/AE button pressed with whatever part of his thumb he can lodge against it for however long he usually keeps it pressed. But he should know in advance its probably not going to be fun.