I would advise that you pass on this trailer also.
Keeping the GVWR of the trailer at or below the truck's "tow rating" is a good rule of thumb, but having towed with Titan/Tundra/F150/1500 class pickups for many years, I believe 7000lbs maximum is a good number for best driving comfort.
When you go much past 7000lbs, and that's LOADED, you run into payload issues with the truck for sure, which makes the ride a little mushy. On top of that even though you have that big powerful V8, it will spend more of its time roaring at 3000-4000 RPMs than you will want to listen to.
Keep in mind that empty weight is NOT what you will be towing, except on the trip home from the seller's. Depending on your camping habits you will have 1000-2000lbs more in the camper along with 300-700lbs extra in the truck.