I have a 2017 Ram 3500 Tradesman with 4wd and 6.7 Cummins Turbo. My fuel tank is I think 32 gals. My guess is when towing, I will have to stop for fuel EVERY day. I could live with every day and a hal...
I installed a 40 gallon tank from the Farm Store and a transfer pump and handle from Craigslist, for a total investment of less than $300.
I simply wouldn't be without it. Now I can stop at rest areas of my choice rather than noisy stinky fuel stations. I can fill up at the end of the day when I am unhooked from the toyhauler and not have to worry about whether I can fit into the station with my trailer in tow. The convenience is wonderful.