As noted, a frequent topic. There are 3 camps; those who never travel with it on propane, those who do travel with it on propane but turn it off when fueling, and those who run it on propane without ever turning it off. From the many many previous discussions there seem to be far more who do travel with it on propane than not. And of those who do, it seems the majority of those do not turn it off when fueling. Gasoline fumes are heavier than air and sink to the ground. It would take a very special set of conditions for those fumes to be somehow blown up and into the fridge vents in sufficient quantities to have a high enough concentration to reach the explosive level at the burner. Make your own decision.
If you use diesel pumps, then there is no concern. Diesel fumes are not explosive as are gasoline fumes.