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 the RDS 63 gal tank with gravity feed. I can carry approx 97 gal and can travel nearly 1000 miles towing before I need fuel. You will be able to stop at the cheapest stations for fuel if you use an app like Gas Buddy.