I have a 2008 2500 CC D/A. It tows a combined weight of 24,500. It goes up and down passes just fine, no issues. The pickup has just south of 150K on it and has been one of the most dependable pickups I have run. 15K worth of cargo would not concern me on a fifth wheel set up, but it sounds like the book answer is you would be heavy. It would likely come down to what you feel comfortable with. As suggested, I would go through it. Debris is famous for getting in between the coolers. I would go through the brakes, these run 16" wheels so the brakes are smaller, make sure they are good. If you don't keep up with it, I would change out all the fluids. Being a couple K over the book spec, with that pickup, would not be enough to stop me from getting the trailer.
