Even that's not necessary; it's a problem that solves itself. If a vagina owner goes into the mens room, they're going to be using a stall. If a penis owner goes into the women's restroom, they're going to be using a stall.

It's not like the gender signs were a deterrent to rapists in the first place. No rapist in history has stopped and said, "Well damn, I can't follow them because a sign says so."