If you have the clothes you need for a wide range of temperatures, and are packing light, you have only a few of each item at most. Thus, frequent laundry for a small number of items.

If you plan to do much sink laundry, a flat drain stopper that is really flexible is great to have along. Campgrounds rarely have drain stoppers in the sinks. Mine is silicone and is flexible enough to get a good seal. They no longer sell them where I bought mine, thus I have no suggestion on where to buy.

My clothesline is thin cord, maybe 3/32 inch or so, 25 feet long, 10 clothespins on it. Packs down very small and weighs almost nothing.