You have a couple options. My recommendation would be DP-Tuner. They are fantastic people with a great reputation and customer service.
If you just want one tune - you can send your PCM to be burned. That's your cheapest option. For a 7000 lb camper, I'd recommend you get the 80-econo tune. That will allow you to drive the vehicle loaded and unloaded with great results. If you went with a multi-position tuner, I'd get the F5 and put the 60 econo, 80 econo, and 80 tow on it. That will give you a bit more flexibility although the price goes up.
For any tune, it is recommended you have gauges - transmission temperature, exhaust gas temperature, and boost at a minimum. I would HIGHLY recommend you do the 6.0 transmission cooler upgrade as well.
Enjoy the vehicle - you just bought the best engine in the best year ever made.