Just thought of two more obstacles.
When you put that much weight on the large tires they are going to squat and cause a lot of drag. Even more than they usually do. If you don't already have one you would need a monster tranny cooler and I'd be surprised if you hit 5 mpg.
The other problem is a load distribution hitch. Usually TH's require these to balance the load between the axels and I don't believe I've ever seen a drop down LD hitch which would allow the trailer to ride close to level.
There are some really nice pop ups that your truck would be able to handle though, or maybe a light hybrid.