I used to try to fit in the auto diesel bays, but most of the time it is a pain because of goofy 4 wheelers rushing in and out of the bays or leave their cars at the pump after fueling up to go in to get a bag of potato chips and coke:(. Drives me nuts. But most of the time I find manuvering your RV around in limited spaces a bigger pain:(.
Now I just pull in the bays for the 18 wheelers where there is plenty of room and it is easy to drive in and out. After I drive into the fuel bay, I look at the number of the pump I am going to use, then I go directly into the casher and take care of the credit or cash payment. If I have to go to the casher to pay, I fuel up I move the RV and truck out of the bay so another 18 wheeler can drive in for fuel and I am out of their way. Be sure and check the size of your fuel tank opening, the 18 wheel hose nozzles are larger than the regular gas nozzles. The truck pumps also pump about twice as fast as the car pumps:)