As part of my return home clean up procedure, I add about 3 gals of water and a small amount of Odoban to the Thetford and run the pump to circulate it. Odoban is a cleaner/disinfectant used in many vet hospitals and is very effective. After sitting for a few minutes, I drain it. This has worked very well for me for years and does not seem to hurt he seals. I also found that applying a little RainX ( for plastic) the the inside of the bowl makes everything
slide down better and keeps it clean.