What **Anaamika **said. Washing - really washing - by hand is very hard work. Now, most of the time you won’t need to really wash, you’ll just need to defunkify, and that’s not hard. For anything that’s washable, my recommendation is to throw it into the tub while you take a shower. Plug up the drain, stomp your feet, kick 'em around and rinse clean when you’re done. Squeeze out the excess water (but don’t wring the fabric, twisting is very hard on cloth fibers) and hang to dry. I don’t even bother with detergent - the shampoo and body wash rinsing off of me is enough to do the trick.
If you don’t have a tub in the shower, then yeah, a sink is the next best thing.
If you don’t have access to a basin at all, consider bringing a cheap bottle of vodka and a spray bottle. Hang the clothes and spray them with vodka until they are quite damp and then let them dry. The alcohol in the vodka kills the odor causing bacteria, and when it dries it’s odorless. This also works on clothes that are dry clean only. Old costume shop trick from college - dry cleaning solution was outside the budget.