In bed diesel tanks

60 ga. RDS gravity fed. Get fuel when it’s cheap and roll on.

I have a simple 25 gallon Enduraplas tank. They make a 55 gallon tank also.
It is a simple transfer tank with a nozzle that you manually fill your tank with. I use a 12 volt jump box to power the built in pump.
It does the trick no installation required. I can move to my next truck or put it in another truck in minutes.
Not quite as convenient as a piped in tank but just as useful. Easily removable if you want the space back.
Works great. Use it when you want . Remove it if you want.
Very versatile and flexible
Enduraplas Tank

I have a 35 gallon tank in the bed of my Dodge dually and simply love it. Best money I've ever spent on something that wasn't motorcycle related.

I love that I don't have to check out the fuel stations ahead of time to make sure I can get in, and, more importantly out, with that 40' toyhauler in tow. I can carry enough fuel to only have to fill up at the end of the day when the 5th wheel is not hooked up. Lowers the daily stress level considerably, especially if you're traveling the two lane highways with fewer big ol' truck stops.

I like taking breaks at rest stops, or parks rather than using the fuel stop as break time.

I like being on my schedule rather than the trucks fuel tank's schedule.

Okay, the cons...uh...well...hmm...it does cost more when I fill both tanks.