So sorry to hear about your son'e accident. I ride a motorcycle, and hitting a deer is always of concern. I am glad to hear that he is on the road to recovery.
You have got good advice, and are doing the black/gray tank ops just fine. Only thing I would say, is that I never, ever add deodorant-type chemicals to my tank. What I do, is go to Lowes or a hardware store, and buy a can of septic-tank treatment, which is the friendly-bacteria that speeds up the liquify process, but digesting the solids.
USAF 1965-1971; USCG Master
2002 Horizon 36LD - 2000 GMC Sierra 1500 4x4
Indian River, De