The commercial fifth wheel on the truck will hook up to your fifth wheel camper, no problem there. You may have to slide it back for turning clearance to the trailer vs. the rear duals/mudflap/fender on the truck. You will need an electrical interface like the Jackelope to convert the separated brake/turn signal used on commercial trucks to the combined brake/turn setup used on an rv 7 way plug. Also you will definitely need an air pinbox on the trailer to cushion the harsh ride and not beat up the camper. The suspension is built to haul a 50000# trailer, and an 18000# camper takes a beating. Most of the guys using a HDT to tow their camper use an air hitch like the ET Jr. or Trailersaver (I have a trailersaver) but that won't be an option for you if you want to use the truck for commercial service as well. Check out the HDT Rally
site, they have a whole resource section for using an hdt for rv service. I am planning the same jump myself, currently towing with a medium duty GMC, and want to move up to a semi next year. Good luck and welcome!