"Get over it"? The "only easy or realistic notion" is the toilet idea? Thanks so much for the encouraging welcome.
Paula, thank you very much for your comments; they are very helpful. Only western WA is rainy; the eastern part of the state is desert. I've been looking there (on Craigslist), and have seen some promising ads. My business is seasonal, so I have the summer to work on the trailer and find an off-site kitchen solution; your idea is brilliant and I'll check into the possibilities.
Fiamma, thank you also for your ideas, and all the links. I really appreciate your taking the time to compile that list.