rudyp,
Not sure why the Ford Fleet guy does not know the difference between towing & hauling. Cargo capacity is your limitation. As others have suggested, get the truck weighed ready to go camping. What is left over after subtracting the weight of the hitch is what you have left for pin weight of a 5er. I went through this a few years ago. Had a two year old 2500HD and wanted a 5er. I thought I would have no problems towing the trailer. After looking at my door sticker and weighing the truck, I quickly realized that I would be over my GVWR pulling the empty 5er off the lot. I opted to get a bigger truck and went with a DRW so that I could expand in the future.
In the end, it's going to be your call, but I doubt you will find many here that will endorse the plan to haul this 5er with your truck.