I once camped with a large group w-a-a-a-y out in the woods and there was only one RV along. Everyone else was tentcamping...the rule-of-the-RV toilet in that case was just the opposite: No number ONE. This as a way to avoid premature filling of the black tank due to numerous daily visits, especially by the children in the party who seemed fascinated to see how much water they could use to flush.
Rationale was that number one was easily managed/disposed of via simple privy pits, all TP being put into a container for disposal. But folks were welcome to use the toilet for their (usually once a day) number two routine.
We did have to impose a further "diarrhea, if claimed by children, must be independently verified" rule. :B
No problems dumping at the end of the trip, BTW...nothin' like using lots of water!