11screw50

I think I read somewhere that the aluminum body saved something over 400# and the rest of the weight savings came elsewhere but it was a lot of nickel and dime type stuff.

mass-hole

The ecoboost is plenty capable at altitude. I bought my truck in Massachusetts and a month later moved to Utah and live at 6500' now. I have also gone through some 11,000 ft passes in CO and noticed no reduction in power. There is a little bit more lag since you have to get the turbos spinning faster to make up for the thinner air but I doubt you would be in and out of throttle much towing a trailer in the mountains, so I really dont think this would be a problem. A diesel would likely fair a little better in the lag department since they tend to keep the turbo spooled and making a little boost even at idle, but I still notice more lag than at sea level in my diesel Jeep liberty.

Like others said, payload is the biggest hurdle with the half ton trucks, however, I have looked at quite a few 2015 and 2016 supercrew 4x4's and none of them have been below 1700 lbs payload.

If your current 2007 5.4 can tow the trailer then I have a feeling you will be blown away by the ecoboost. Not only does it start out with more power, but it wont lose 20-25% at your altitude.

TooManyVehicles

Or, the OP can do what I did. Get a XLT SuperCab (instead of Crew Cab) with the 3.5L EB. My payload sticker is 2046# and I have the 302A package. Not as good as the F350 I was looking at, but considerably less expensive and a much nicer daily driver.