I put them in the shower. Leave them for a couple minutes, turn, flip, etc. For stuff that you can make smaller, get one of those "kitchen sink" packable tubs. A folded up wetsuit will fill inside. If you remove the wing from the backplate and fold it you can do the same.
Sea to Summit Kitchen Sink - 20 liter
Use a spool and double ender to make a clothesline in your hotel/apartment/rustic beach cabana.
I do similar. Even buying a tub for a few dollars locally isn't bad. I've used a cleaned out borrowed garbage can too.