Interesting project! I use the same jerry cans for water and gray as well, but I have a sink and hand pump. Are you planning to fit one/either? I've always thought that the secret to a good livable build is a ready bed (that you have, looks comfortable!) and a usable galley. Somewhere on this site is a link to a (Avanti?) box kitchen. Mains powered, but no reason why you couldn't fake something like. I have lived out of a Trangia cook set, they work pretty good and can be easily fixed in place.