Been pulling a fifth wheel with diesels for 17 years now and I always use the truck lanes; enough clearance, easy entry and exit, etc. I almost drug an AC off the top of my fifth wheel the first year, before I realized I needed the truck stops, not auto friendly stations.
Many stations have RV spots, beside the auto islands, but you usually have to back out when you get through. Backing a fifth wheel with autos zooming in and out next to you is scary. You might get a slight discount for using the RV island, but it ain't worth damage and repairs to you rig later.
