I put the rds 60 gallon transfer tank/toolbox in my dually. Has it's own pump and fuel nozzle. That gives me supposedly 92 gallons but that's not all usable. When we stop at rest areas for bathroom or to walk the dog I'll fill up my truck tank out of it. All I had to do was bolt it down and run wire to the battery.
I fill up when we unhook for the night, or stop at truck stop and use my efs card if I see a deal on the interstate.
https://www.northerntool.com/shop/to...9657_200609657