I hate stopping to fuel up. If our current Class C motorhome carried enough gas for a 1000 mile trip without fueling I'd be a happier camper. That doesn't mean we don't stop every couple of hours for other restful or beautiful reasons - but often going out of our way to find, and stop at, a busy (and ugly) gas station to fuel up - no way.
The DW and myself decades ago built a camper into our new at the time 1972 Dodge van. One of the first things I did was install a 40 gallon aux gas tank to supplement it's stock 26 gallon one. Those two tanks together gave us a range of over 1000 miles. That van's 318 V8 with long gearing averaged 16-18 MPG, which is tough to beat with even today's "high tech" engines. Of course gas back then didn't have ethanol in it.