We camp mostly at state parks, often only 1/3 of the sites have electricity. I'm not big on reservations so we tend to end up in non electric sites with the tenters. These sites are often in the wooded section where sat tv will not work, so very likely solar would not work well either. We run the genny for an hour a day to charge batteries, with 70 gal of fresh water and 50 gal grey/black we could easily go a week with out dumping tanks and refreshing water.
Seems like a lot of work and cost to redo the toilet situation. Just make sure its what you really want to do because it may be nearly impossible to sell or trade a unit with a composting toilet should you change your mind or need to quit rving.
Just a few thoughts. Good luck!!