You are limited only by your imagination.

If you use that bay you will have to consider cold weather camping. You will have to heat that bay or winterize that tank when in colder climates.

I have also seen some gray tanks with pumps and that water used for flushing the toilet killing 2 birds with one stone.

A long time ago Winnebago also had an injector nozzle that sprayed the holding tank into the exhaust system