Judithgap:
We have the same basic set-up you're looking at. We have a 2012 F350, diesel, crewcab, 4x4, with the camper package. We haven't made any suspension modifications to the truck.
With the addition of 2 children, we moved from an 820 into an 855S and couldn't be happier. Lance did a great job on the 855S. For a short bed camper, the four of us are quite comfortable. The sleeping accommodations are especially nice, because the kids beds can be put together in a couple minutes.
The camper feels comfortable on the truck and handles the load with confidence. In fact, during our most recent trip, we drove in significant winds for several hours and the truck probably handled better than most cars!:)
I think you would be happy with the package you're looking at and I would be happy to answer questions you may have.
Best of luck!