I know just how much gear you take Bobbi -I've lugged half of it around a campsite for you remember!
Put the sink in one of these trailers. Saw this idea several times around the site of the Manchester NABD do. Obvious but it had never occurred to me. Car roof-top boxes make perfect trike trailers. Lightweight, aerodynamic, stylish, waterproof, lockable & they come in several colours & sizes. I've got absolutely no use for one cos I never go camping but still quite fancy one of the long thin torpedo shaped ones. Big enough to pile all the bike gear in, the tent if I had one, a week's shopping, spare car battery hooked up to the sound system & disco lights, fridge, kitchen sink....