Thought I'd resurrect this thread with the outcome. A few days ago I traded in that 2016 F150 for a 2019 F150, with pretty much the same set up. 5.0L V8 with 3.31 gearing. The newer one with a 10 speed tranny as opposed to the 6 speed in the 2016. Also came with the Tow package.
The 2016 worked flawlessly towing the 5100 lb CD-22 over the Midwest, Rockies and other mountains out west. Running without trailer, at 80 mph out west, I was getting around 19.5 mpg. Back at 70 and slower, I could get 22.x mpg. Towing, depending upon the wind and mountain range, anywhere from 9-13.4 mpg. Average flat land no wind seemed to come in around 12.3. Pulling the boat up the Rockies with the 2016, there were times the tranny would shift all the way down to 2nd gear, while running 65. Because it was sitting just under red line, I would let up on the peddle and slow to 60. It'll be interesting to see where the 10 speed in the 2019 downshifts to. The F150 felt very solid pulling the CD-22. I did install a standard Tekonsa Electric Brake Controller, which also worked well with my tandem axle electric brakes. With the new truck, I elected to go with Ford's Electric Brake Controller. Hope it works as well. The new truck also has the Electric Locking rearend, something my 2016 didn't have, and a factory backup camera. I added a backup camera to my 2016, but don't think the aftermarkets are ever as good as the original factory installed units. I expect the electric locking rearend will help on slippery ramps or starting up on icy roadways. (As the non locking rearend on the 2016 basically became 1-wheel drive on anything slippery, unless I locked in 4WD.) Colby