We finally got the off-grid laundry system set up!
It consists of two not-very-large builder's trugs, a home-made stool at just the right height to allow me to work without messing my back up, a scrubbing brush, some home made soap (the ecover is for washing my hair, which doesn't like 'real' soap for some reason) and a water supply, heated either by the sun or by a gas heater according to the weather.
Now we have it all set up and working, I think it works out less hassle than attempting to use a machine.
I always put the laundry to soak overnight - it does half the work for me like that! Just put the dirty clothes in the top trug with a dollop of soft soap (I make it with extra water so it stays soft enough to scoop out) and cover with cold water.
Next day, if it's cold I put that trug down on the floor, fill the other one with warm water and another dollop of soap and transfer the clothes into the clean water. I can either tip the water out onto the floor and let it find its way out the drain, or I can grab both handles of the trug in one hand and carry it out to water a tree with, depending on mood and how much the plants need water at the time. If it's warm, I just use the original trug with the cold soapy water. Then sploosh and scrub each item as necessary, dumping them into the now empty trug. When everything has been transferred, swap the trups again. Rinse and repeat as necessary. Then I hang them on a clothes horse under a roof to drip dry, and finally bring them into the house to finish drying after a day or so.