From time to time I'll head down from Roadrunner, get b'fast at Duners Diner, then go in to Gordon's, up and over Test, and then dune all the way back up the East side of the closures (hitting all the big hills). Usually we go back to RR after China, but sometimes we do Lizard->Brawley Slide->Olds just to finish the journey, then cut back out to RR. It's def more of a SxS run than a big car run, though I've done it in my Potter. The potter had a 26 or 28 gallon fuel cell and it was never an issue. Doing it in SxSs I bring fuel in a high quality jug strapped into the floorboard in an empty seat. Yes, it's still not ideal but hey you're sitting on the gas tank in a RZR anyway and it's WAY better than in the bed. We start the run by going down sand highway and take it easy, when we get to DD we empty all the gas cans into the rigs so that a) we don't have fuel in jugs in the vehicles any longer than absolutely necessary b) we don't have fuel in jugs in the vehicles when doing any actual duning.
-TJ