I'll answer anyway

I don't know yet. 90% of my rides are 3 hours or less, and with a little forethought I can get away with not peeing for the duration. But when I wear bibs I do make sure I a) have a somewhat decent sports bra underneath and b) have a jersey with a full-length zipper, in case I need to go be discreet behind a bush.

To be quite honest, that little doohickey that keeps the straps of my PI bib together is the worst problem, when I've got all the rest wrestled off and am in a HURRY!