Upgrading from Travel Trailer to fifth wheel RV

I have a 2007 Arctic Fox 29V Travel Trailer with a Hensley Arrow hitch that holds the camper in line during towing, but am thinking about upgrading to a slightly larger Arctic Fox fifth wheel sometime in the next few years for more options and greater livability during long stays. I just bought a RAM 3500 long bed crew cab with the 6.7L Cummins high output + Aisin heavy duty transmission, so pulling a larger trailer will not be an issue. Currently, I carry a quiet Honda 3000 watt generator & 50 gallon spare fresh water tank in the pickup bed to power the trailer (if necessary while staying in rest areas enroute the campsite) or remotely refill the 67 gallon 29V fresh water tank while staying in electric only sites, but was wondering how people with a fifth wheel RV refill their fresh water tanks if not connected to a water supply? From what I can tell, the fifth wheel hitch takes up room over the rear axle preventing being able to carry an extra remote tank, and the fifth wheel hitch pin glides into the receiver preventing hauling a tank behind the truck mounted fifth wheel hitch. Right now, the only way that I can see how to do this would be to tow an additional small trailer behind the fifth wheel that could be disconnected and towed by the truck for use in making fresh water runs. But, in doing so, creates another problem of what to do with the trailer when parked at a campsite. Any help or suggestions would be appreciated.