Here are a couple videos with some clothes washing tips.
I didn't mention that I also have a bucket that I use for bigger clothing so I have several washing containers.
One thing (of the many) I've learned in van life is that I can't be obsessive on the washing and just be thankful for as clean as I can get the clothes because I often have to work hard to conserve the water, even the rinse. What I do then is when we get the opportunity to have unlimited water, I rinse extra times and it's all good. And oftentimes there isn't a lot of time to wash depending on where we're parking so it could be a super fast washing and then keeping in mind that we can't be doing it all in the wide open especially when it comes to drying them. 90% of the time I have to dry them inside the van so I also have to be careful how many I do at one time. To stay on top of it all, I wash things as soon as they need it so that the pile only builds up when we don't have water or when it's wet and cold out for long periods of time. It sure makes a person super thankful for whatever can be done to keep clothes clean. Hope that all helps:-)