navegator wrote:
Before you go boondocking, the tank is totally empty, when you guys start peeing there will be enough "water" for the chemicals to do their job,
First, the tanks are never "totally" empty as there will be some condensation and moisture in there. If left alone for too long, that will MOLD. In my book, risking a nasty mold growth is not worth worrying about wasting a couple of gallons of holding capacity.
Second, what you claim above depends on how many people you have with you and how much beer they drink. When I'm out alone and using the commode only mornings and evenings, it might take several days to accumulate a gallon.
In summary, I think that your approach is NOT a good one.