When I started driving I had a 78 Chevy with a 350. It was a fun truck that I had rebuiltin my teens. My next truck was a 94 dodge 2500 Standard cab with a 360. It was decently powered as I didn't tow anything at the time. In 2002 they came out with a hemi and I had to have one. My theory back then was I could buy a lot of gas for the 6k option for the diesel. I loved that truck until I bought a bigger camper.
We started with a pop up and then got a 26' travel trailer. While the truck towed it decently on flat terrain in the mountains it really struggled. I have been telling my wife for years that when we get a new truck it will be a diesel.
This year I bought a 2015 ram 2500 with a diesel. I also bought a new 36' trailer. The trailer gvwr is around 10k. I can't believe how good my new ram tows it. Sure it's mostly because of more power but being able to tow under 3k RPM's really makes it MUCH quieter in the cab.
I would recommend buying more truck than you need. I always regretted buying a gas motor because I didn't want to pay the extra for a diesel. I still think if I would have bit the bullet in 2002 I would have a paid off diesel that will do what I need. Oh well. Now I have payments again but I now I look forward to pulling my trailer rather than hating it. I am getting 10-11 mpg pulling so far. With my hemi I would get 6-8 mpg.