Did you ever consider having a system for collecting and purifying rain water?
Yes I have- actually with Shachagra's roof it would be easy. Since the solar panels are inset, water escapes from only 3 places, two drains in front and off the back edge. I could divert the drains to feed into the water tank and park on a downslope when it rained. In a heavy rain the water comes rushing out drains below the truck. I have filled the tank using 5 gallon buckets I put under the drains. Water was so easy to find on the trip, I just did it to do it.