when I lived in Honduras I used a wash board

for 6 months maybe ?
till I found out this little old lady would do my wash for a dollar and it would come back folded and cleaner
just swimming in clothes if you can gets them quite clean amazingly
the other thing I used to do was a mesh bag and no soap nothing just tie it off in a fast part of a stream or river overnight if you are around one
should say CLEAR water source of course but the swimming got them cleaner than the bag method
throw over bushes to dry ?
these days I am usually back in civilization or close enough every week so just bring to a laundry mat