I'd keep it as light as possible. You might consider a hybrid (HTT) trailer - one that has pop-out tented beds but otherwise is like a regular trailer in height. More space for the weight. With your truck's specs, I'd say keep the GVWR of the trailer (NOT the same as "dry weight" - at or under 5000 lbs too. That will keep the length down automatically, as there are no trailers I'm aware of that are longer than about 25' with that kind of GVWR. At the very least you'll want to upgrade your truck's tires at some point.