Let me inject here a comment re: compost toilets. Since we have one and have had it since around 1985, I advise people who want to know that compost toilets in cool climes are simply not great. The composting process needs warmth to keep the bacteria and other agents working efficiently; in fact, in cool temp's one cannot tell they are working at all. In a higher-use, commercial situation, it will be a constant source of hassle. Basically, they'll have to be emptied out frequently and it ain't pleasant and you are faced with what to do with the material that was cleaned out....
I suppose it would be possible to keep the toilet chamber heated somehow, as with some of that hot water, but, again, in a commercial situation there will be, trust me, some unhappy "campers." And, the heating system to do so would, in my opinion, add another level of technology, upkeep, and hassle to the system.
There are Incinolets, the electric toilets that burn the stuff, and the propane ones, likewise. Of course, you would need more electricity or propane to do that. I looked into both; the electric ones use far more electricity than one would want to provide with PV or wind [except at the exact time the wind was blowing sufficiently], and there was no way I was gonna buy propane or any other such fuel to run my toilet. If I recall [and it was some years ago that I looked into this], the co. selling propane-fired toilets suggested that for a 2-person cabin, one could probably expect about 30 gal. per month propane useage. I have no experience to tell me whether that is accurate.
Not trying to be discouraging or anything, just realistic.....