We prefer to fill the truck without the 5th wheel attached. We have an auto leveling system so it is easy for us to disconnect/connect even during an overnight stop. We put in an after market replacement tank (61 gal) so we do not have to fill up while traveling. If we do have to fill while traveling, we use the truck pumps. We fill up, move forward so the next vehicle in line can fill up, and then go in and pay. We have only had to fill at regular pumps a couple of times and we are very careful of the station we chose. If you fill at the truck pumps, be aware that they also despense DEF.