fantastic fuel mileage for a full size truck.
I have owned several full size trucks and towed with all of them. For your usage described, any full size truck will do just fine. I love towing with an EcoBoost engine over a naturally asperated V8. I could set my cruise at 80 towing my 20 foot pontoon with the 2.7 Eco and not worry one bit about it.
With every V8 I've ever owned, you can't set the cruise and tow. They have to downshift way too far to get into their power band to get up any decent sloped hill. That includes Ford's 4.6 (a crappy engine in retrospect, talk about underpowered), Toyota's 5.7 (a fantastic engine) and Nissan's 5.6 (both versions, and both fantastic engines). I have been in friends' Rams as they towed with the Ram 5.7, and the same applies.
Now, all that said, I was not impressed after watching some YouTube teardowns of the 2.7. Ford, do better. The 2.7 is a great engine design. But to save a few bucks there are way too many cheap materials used to accomplish some of the more important tasks. I used to sing the praises of the 2.7, but I can't do it anymore.
I've heard good things about the 5.0 Coyote. If I'm buying used, that's the Ford engine I would get. Just make sure it's before they slapped variable cylinder management on it. I hate that they did that. Every manufacturer that has ever tried VCM has had issues, and none of them have figured those issues out.