Hello,
I can completely understand the desire for clothes washing convenience in your van. I have a portable, manual little wash machine that works similar to a salad spinner. It has a lid and a drain hose, you fill with clothes, water, detergent, close the kid and rotate it around back and forth with a handle on top to wash the clothes. Then open the drain and spin to get most of the water out, and refill/repeat to rinse. It’s pretty handy and small so it doesnt take up too much space. But it wouldn’t work well for bigger items like jeans or bedding. Something like this:
https://smile.amazon.com/Portable-Hand-operated-Traveling-Apartments-Travelling/dp/B08M65WH19/ref=mp_s_a_1_17?dchild=1&keywords=camping+washing+machine+manual&qid=1627064313&sprefix=camping+washing+machine&sr=8-17