Well, I need maximum diameter with minimum depth. (depth of sink plus drain elbow <= 4") Boy, I could use a 9x13 pan even then, little modification to the drain area slope with some basic pressure. Buy at salvation army for $0.50. Rim of wood. Drain as you say... of a basic screen and 1/2 inch fitting and elbow.
If you want to get REAL simple, I have been thinking of using a hinged fold down sink, that rests on top of one of those new kind of liquid laundry detergent jug. the ones with the caps that drain inside the bottle. Then when filled just go drain it, swap in a second one... Lots of possibilities there. If you are going that route and don't want to go "power faucet" yet, you can get one of those camping water bags with the spigot, that has a hanging point, opposite the spigot. Just hang it over the sink.
I now have an idea to have my fill point at the right front corner soffit/eaves... That would give me an access point, semi-hidden, with some elevation for the venting. I'm wondering now, we have the grey water storage and drainage. Even slip some chlorine down there for cleaning, is there grey water flushing? (pressure inlet -> flow through grey tank -> to grey drain?) to clear out any sediment of dirt?
location of this in my build documentaryhttps://sites.google.com/site/pchistori ... d#wtr-plan
FYI: I'm jumping almost same topic between two forums.
here: ( a new one )
there: ( Plumbing sink drain )
The build is the thing.