Flying J's have their LP tanks on the drivers side at RV lanes. I never use the RV lanes!! Too many cars in them!!
You don't have much choice on using the RV lanes or not at Flying J if you want propane. Flying J has always had good prices on propane and the prices have barely gone up as oil has skyrocketed in price.
The only reason to use the RV lanes to fuel a converted bus is because Flying J does not charge the 5 cent per gallon credit card fee in the RV lane. Otherwise, the truck lanes are much easier and faster.