I haven't read all the comments and I'm sure by now most have said you need a 3/4 ton and maybe a vote or two for 1ton. Hogwash. Keep to the specs of the truck and the truck will do its job.
The new Ford's have no problem towing their rated capacities. These trucks have been tested to these limits to a standard. Not like the days of old when the manufacture did what they wanted and made wild claims based on marketing hype.
Video F150 towing 9500 pounds up/down the IKE. 60 mph up 7% grade towing 9,500 pounds.
https://www.youtube.com/watch?v=_z4isefQedA
I don't have max towing or max payload and have no trouble towing 9,300 pounds (7,000 pound 5th wheel and 2,300 pound boat). I crusie at 60mph, no issues with braking or getting up to speed. I average 8-11mpg towing, depends on headwinds. Last weekend I made a 450 miles round trip with just the camper and averaged 10.4 mpg. It was 11.8 heading to St. Louis, and less coming back (headwinds). No wind going there. Yes, I triple tow with a F150. Yes, I would tow it through the Rockies, and yes I grew up in Summit county, elevation 9,100' above sea level. I was at the Eisenhower tunnel wihen it opened. Before the IKE we used to drive over Loveland pass to get our monthly grocieries in Denver. The pass goes above tree line, something like 11,000' or 12,000'. The tunnel is a nice shortcut.
As a DD. I average 19-20mpg around town during the summer and 17-19mpg in teh winter. I let it idle about 10minutes before I leave. I love remote start. towing only the boat I average 17-18 on the interstate, again doing 60mph. Last summer I made a 1,000 mile family vacation (week long trip) and averaged 24.2 mpg. No 250 or 250 cam touch those mpg.