Here is a simple one anyone could build into their trailer. ZERO WATER use.
Human waste liquid is suppose to go in different container. Two buckets with one for each.... takes up too much room etc etc. an easy but expensive solution (unless you make your own which does not look hard) is a Mr. Miser mounted on the wall near by.
It is a LOW to NO water use unit and would only take up 4" depth of wall space with bag installed inside space to catch liquid for later disposal.
There are solutions adaptable to the Miser unit that woman you can use. You can find them via google. I posted a bit about them earlier but someone found them objectionable?
and removed the thread. Freshette is one of many. Also great for woman who do not sit and stand easily on toilets. There was a thread on a disabled camper lately that this could help actually. Haven taken care of elderly and handicapped folk for years I got a little knowledge in that area.
Even if compost toilet is not your idea of.... "acceptable". The Miser unit could be a small tucked away thing used only at night when you dont want to walk to the CG restrooms. Take care of more solid business in the day time?