We towed out 5,500 lb RV travel trailer 3,000 miles last year from MN to the Gulf Coast and back with our Ecoboost. We got 11 mpg towing at 60 mph. It rarely needed to shift out of 6th gear; even in the hills. (3.73's) We saw 4th gear twice on an extremely steep and long hill (same hill both ways). It is a 3.5 liter engine with 420 lbs of torque; max torque at 2,500; 90% available at 1,800 rpm.
IMO, it is the equivalent of a small displacement diesel; but with more HP, less maintenance, and cheaper fuel; extremely quiet. Remember it is only 3.5 liters. Double that to 7.0 liters, like many of the big diesels, and you would be looking at 840 lbs of torque.
It really is a unique gasoline engine for towing and it works great. It's biggest limitation is probably the "1/2 ton" chassis. Payload can limit its capability although there is a HD payload option on some configurations.
2012 F150 FX4 Ecoboost, 2016 Surveyor 274BHS
2003 Yamaha FJR1300, Demco Premiere Slider
1969 John Deere 1020, 1940 Ford 9N, 1948 Ford 8N
Jonsered 535, Can of WD-40, Duct Tape
Red Green coffee mugs