Lots of tankage and use the mainsail to catch rain. Instead of raising it all the way you leave a pounch at the bottom, all the rain that hits that square yardage comes out the end of the boom like a gusher, conduct it by bucket usually. Anchored out bring water with every trip to stay topped up. I also scavenge likely looking wood/driftwood for fuel, have a little wood locker, use that in the grill.
Good idea. Where are you at? Roughly