The EcoBoost has plenty of towing capacity. But what we ran into with pulling an 8000ish loaded bumper pull toyhauler was a lot of sway issues. The F150 was just too light to stay grounded, no matter what we did for the set up in terms of adding airbags, WD hitch, Equalizer, driving slow, etc. Had a few scary incidents that made it enough for us to upgrade to an F250, which worked great, and now we have an F350 dually (which was purchased more for a future trailer vs the one we have now).
And, for the record, when we did tow with it, we got 9mpg. We get 12-13 with the 350, plus it has a much larger gas tank so we don't have to fill up every 2 hours.