fifth wheel gas stops

Plan your route and determine, as best you can, at what mileage interval you should plan on stopping for fuel (leaving the appropriate reserve amount still in the tank - don't run it near empty). Use Google Maps or Google Earth around the points you identify to find and check out the satellite view of potential fuel stops (search for "gas stations near . . ." the town where you plan to stop). You can even go down to ground level in Maps & Earth to check things out from the highway. There is a distance ruler in Earth you can use on the satellite picture to check out turns and clearance if need be.
There are several apps for smart phones & tablets that can identify fuel stops on routes and maps.

Good luck.