Congratulations on the new truck.
I have an '03, 3500 SRW, 4X4, NV-5600 & tow a Nash 25-S bumper-pull trailer that probably weighs in the vicinity of 6000+ lbs. I did not want to go through life without trying one of the suspension systems offered. I did not want to raise (lift) the truck, much, at all. Just wanted to make the ride more comfortable on dirt, bumpy roads. I chose the Lorenz Bilstein 5100 System that incorporates new, 2" longer front springs, an additional leaf spring pack for the rear springs that eliminates the overload springs, Bilstein Shocks, etc. It did make the ride more comfortable. Quite a bit more absorbtion of bumps. For example, there are speed bumps in my neighborhood. Anything over 10 mph. & I could hit the bump stops on the suspension. Since the installation, I have gone over the same bumps at 20 mph. & have never hit the bump stops.
I have a Duramax friend that is one of the fussiest people that I know. He hated my Dodges. I took him for a ride in the '03 after the suspension upgrade & did not tell him what I had done. We went down a dirt, bumpy, washboard road in Quartzsite, AZ. We got a few miles down that road & he mentioned that the truck was much more comfortable to ride in.
Core, Carli & Lorenz produce suspensions that may help you create a more comfortable ride. I'd get in touch with them & see if they have sold their systems to anyone in you area so that you could go for a ride.
I'm not sure that this information or these systems would help you but, it's worth a try.
Best of luck.
BTW, I just got back from an RV vacation & ran across a guy around Pueblo, CO. that had just bought a new Dodge/Cummins & loved it. He has an '03 with 465,000 miles on it & loved that truck. He likes this one better. He has a trailer on his truck all the time.
Joe F.