My two centavos:
If it is an emergency, that is one thing. Otherwise, here is a case of what happened to a friend of mine when he allowed people to use the bathroom in his rig during a wreck-caused traffic jam:
First, it was 1-2 people, someone used the preggers excuse. Then, it became a line.
The requests for a bathroom became demands, with people saying, "you let them in, why not us?"
The black tank wound up full, but people kept using it anyway, even when stuff was at their feet. Since the bathroom sink was plumbed to the black tank, it only made it bubble up.
People finally stopped demanding their way in when the entire trailer smelled like sewer.
Stuff in the bathroom and other places of the rig mysteriously vanished, be it an electric shaver, smartphone chargers, and other items.
The bathroom had damage to it, be it someone sitting on the sink, or the doorknob smashed into the wall.
The black tank was clogged because plastic bags were tossed in there, as well as maxi pads, "flushable" (hah!) toilet wipes, paper towels, and other stuff.
Total repairs needed to make the trailer habitable again? Was in the thousands, especially due to the black water on the floor, but furniture had to be fixed, the black tank had to be dropped and replaced (as the pump truck couldn't dislodge some of the harder plastic items like a large plastic disc and a deflated basketball that were in the tank). Then, there were the items stolen.
My lesson from that? My current TT stays winterized since I mainly use it for renaissance faires in the winter, so there is no water. Thus, the toilet is not functioning. Once I get a campervan, it is a converted van with a bed in it for me; no more.
