Wow, can't say I've ever given much if any thought about where to get fuel next with the exception of non E or race gas for my sleds or the first trip up the Alcan highway, and even that trip I just carried 5 gal just in case and called it good.
To the OP, if pulling into fuel stations is intimidating you then you need some more practice with that big camper, IMO. Or get a slip tank or Titan or Transferflow tank so you don't have to re-fuel with the 5ver attached. You could get a used slip tank with pump for a few hundred $ and carry 40-80 extra gallons.