That's interesting I know you can pull a lot of water out of the ground that way. how much more water could you catch if you had the plastic dip in the middle so condensate would run to a central point. like a reverse pyramid. .
like something polished that would reflect the heat back to the plastic and create a convection type atmosphere; like a parabolic lens maybe. could do that with cloth hangers and the shiny side of aluminum foil, just an Idea. it's a cool thing your doing and quite interesting good luck with it.
Did you look into fresnel lens from old projection tv's. I'm thinking they might work too with solar panels? Here's an Ebay link to start with.
If the distillation area/pan could be lined with a black plastic or painted black then coated with clear plastic etc this increases heat loading capacity if relying on solar. One issue with the scientific grade stills I have worked on over the years is that they do require cleaning fairly often based on usage rate to "descale" the evaporative surfaces of build up of calcium and other mineral residues. The "Boiler" scale as we call it requires use of a strong acid or physical scraping to remove it
One caveat to distilled water, is that the human body does need the small amounts of electrolytes found in water... so if this becomes the sole water source make sure you eat a balanced diet and if working/sweating thus drinking lots of this "pure" water add some gatorade etc type powder to the water to ensure electrolyte balance.
I'll have to check out YouTube!