Just a few thoughts that are my opinion so take it for what it's worth.
Not sure which F350 you have but assuming a diesel crew cab you have a carrying capacity, according to the Ford literature, of around 5,500 pounds. The Eagle Cap 1200 will probably weight in at a little over 6000 pounds wet so you'll be over the 14,000 pound GVWR by a bit because the truck probably weighs in at around 9,000 pounds with fuel and def. Assuming E rated tires on the truck the 4 rear tires probably have a carrying capacity in the vicinity of 12,000 pounds so they won't be your weak link. Your challenges with the heavy truck camper will be sorting out the suspension so you are comfortable with the way the truck handles under all conditions. Most folks here will tell you to go to a scale and weigh the truck without the camper and then with the camper loaded how you expect to travel. That plus driving it with the camper will tell you a lot about what you need to do to be comfortable and safe. Lots of good folks here who will chime in I am sure.