I studied a lot on getting a RAM 4500 C&C to carry a TC but never ended up building it. When I ran the numbers the 4500 was really close. I have a family of five and a dog that would be in the cab. I was planning to have storage boxes above and below the flatbed because the truck would double as my day to day work vehicle. I was also planning on towing a 6,000 pound boat behind the rig. When I added everything up the 4500 would have done it but it was going to be really close which surprised me. If I were to built a rig like that I think I'd go with the 5500 too.