Oh, and if you use that 1000 gallon tank ... remember that unless it
has internal baffles, it must be FULL while you are driving.
Otherwise, the sloshing will turn your truck over or drag the tank off
the truck. And this is a big problem since you are planning to empty
it in several stages. You could try driving very slowly when it's not
full, but given the kind of terrain you are talking about, I suspect
that won't be enough.

Perhaps you can get a tank with baffles. I suspect that $500 won't buy
it, but I could be wrong.

Or you could simply deliver each full load to just one resident. With
the size tanks you are talking about, you'd have to do some planning,
but it sounds feasible.

Edward