Another view...off road beyond most supplies we are concerned with the LCDs; what will we run out of first that we need.
Just considering the Hawk: Electricity, water, propane. We carry extra water, battery lights, down sleeping bags and a backup camping stove so even if our two batteries can't reach a sufficient charge [solar or truck alternator] to power the water pump or start the furnace we can stretch our stay or egress time.
What puzzles me is to go off road with less that the 26 gallons of water that is possible in our Hawk. Water is the limiter not weight of the water. If the weight of the water is more than the truck/FWC combo can handle then the combo needs to be re-evaluated. The "dummy lights" in the Hawk serve us well and we can estimate when it is time to search for a water source be that a stream, lake or municipal water system. Yes, we carry a water filter; laborious to filter gallons, but an option to extend our stay.
Just my take and your needs may dictate carrying less water. Interesting to read this discussion. And of course I might be wrong.
Phil