I have a 2013 F150 Ecoboost that I bought new with the Max Tow package. I have been more than happy with it both as a daily driver and towing my Jayco 22FB.
Gas mileage depends on how aggressive you drive, but as others have said - towing is anywhere from 8.5 to 10 mpg for me, and up to 18 mpg for regular driving.
It tows like a dream - like the trailer is not even there most of the time.
I now have 77,000 miles on it, and the only thing that is an issue is that I had to replace the passenger side exhaust manifold after my trip to NH this summer. The F150's have a weakness in the exhaust manifolds warping over time, and probably exacerbated by towing.
I recommend the EcoBoost highly.