Your figures are right. You will still be under the rawr, after adding another 200#s for the hitch.
You are going to be over the gvwr of the truck, with a FW actual loaded weight of 14,500. IMO, being a little over gvwr, on this late model 350 will not be a big issue.
You are right to stay within the 7,000# rawr, and of course, the tire rating, which should be more than 7,000.
The Ford oem brake contoller works really nice, and the transmission will help with braking too.
Old-Biscuit gave good advice. Your truck is very capable, as is. You will have the option of air bags, to level the load, if needed.
Hope you find a nice FW, to match up with a great truck!
Jerry
