So at our neighborhood pool - the bathroom does not have easy access. As a parent, a child can't open the gate to enter or leave. There is actually a door that would allow them to get to the bathrooms from inside the fence where the pool is located but it's always locked.
I would tell my son to go behind the bushes and storage room and piss and he's done it ever since. The neighborhood HOA president saw him do it one time this past summer and got mad. I asked him why they couldn't open the door so it wasn't such an ordeal for a kid to use the restroom. He wouldn't budge.
Instruct the youngin' to piss on his foot next time.