Agreed if it's sagging some you could add some bags or get some coil over shocks to help. It's good up to a point, I had a pretty good load on my Dakota with a set and while it was bottomed out I was still able to take a heck of a load before that point. Did the math and was probably around 9000 pounds in the back of my 03 Dakota.
As far as the diesel route, had a guy I knew that kept buying used trucks that were gas and was getting irritated when pulling a skid loader on a trailer as some of the newer toyota's were pulling away from him from a stop. Told him to get a diesel if he was going to keep getting bigger trailers. He rebuilt one engine and it went out again not long after so he did what I told him and got a 6.7l Ford 3/4 ton. While he was pulling a trailer with the pickup on it that had the engine out he lost two tires on the trailer and never even noticed. People were honking and waving while he was hauling down the turnpike towards Lawton and he had probably been pulling it that way for a while. Ended up buying some gooseneck trailers after that including a big dump bed that we probably overloaded and the truck pulled it like nobody's business. Stopping was the one thing you needed to worry about for sure though.
As far as the diesel route, had a guy I knew that kept buying used trucks that were gas and was getting irritated when pulling a skid loader on a trailer as some of the newer toyota's were pulling away from him from a stop. Told him to get a diesel if he was going to keep getting bigger trailers. He rebuilt one engine and it went out again not long after so he did what I told him and got a 6.7l Ford 3/4 ton. While he was pulling a trailer with the pickup on it that had the engine out he lost two tires on the trailer and never even noticed. People were honking and waving while he was hauling down the turnpike towards Lawton and he had probably been pulling it that way for a while. Ended up buying some gooseneck trailers after that including a big dump bed that we probably overloaded and the truck pulled it like nobody's business. Stopping was the one thing you needed to worry about for sure though.