When using a toilet plunger for washing, get the cheap kind with the flat open bottom, not the high-power one with the narrower opening. If you have enough water available, you can use it in the bathtub. Sit on the edge with your (clean) feet in the water and go to work.
If you have clothes that have odor but not much real dirt, wash them in a baking soda solution, rather than detergent. It can handle the body oils and the odor. And it takes less rinsing than soap.
If you use the sloshing-bucket method (on a boat or other vehicle), don't fill it full. It needs room to slosh, so don't fill more than 2/3-3/4, counting water and clothing.
For small items like socks and underwear, keep an eye out at thrift shops for a Salad Spinner for removing excess water. They are a plastic bowl with a basket inside that spins by way of manual power. Google Images will show you what they look like. (You can use them for salads, too, but then you might want to have two. Or not.)
Remember to rinse all clothing well, as soap residue and body friction don't work well together.
Sue