Sorry, if you don't have a pen!s, you don't belong in the boy's restroom.
Moreover, if you're pretending to be a boy and go there, what's going to stop the other boys from "pantsing" you to find out the truth?
Girls posing as boys in boys' spaces are in danger of getting beaten up or even raped.
Think it through, young lady.
A single use, gender neutral bathroom solves those problems.