We had that problem a few years ago. Lately I installed a household toilet. A one piece type because I didn't want the tank vibrating loose. I adjusted the tank level so we get about a 3/4 gallon on the half flush button and less that a gallon with the full flush.We carry 150 gallons of fresh water and 165 gallons of waste water.When we're at a campground we seem to dump every other day or every third day. The washer dryer use up water.When we're dry camping we go about a week or 10 days.This was our solution , now you can flush any time you want.Frank