I.m wondering if you could construct a modified solar still where you heat water with a small fire inside of a solar still. The steam would condense on the bag as it would from the normmal drop in temperature and run down to a collecting container. I think the collecting coontainer could be in the center and one or more fires on the side.

Another way might be to feed the tube from the top of a covered container into a solar still where it could condense.

I would love it if someone can figure out a way to set it up.