I’ve owned 3 different trucks in the recent past
1) A V6 with 6 speed transmission - 3.55 rear end
2) A V8 with a 6 speed transmission — 3.55 rear end
3) A V8 with a 8 speed transmission— 3.92 anti slip rearend
#1 got poor mileage when towing and constantly shifted gears if it thought it saw a hill
The engine was designed to pull an empty truck on a downhill grade IMHO
#2 towed okay but you could tell by the sound of the engine and the transmission when there was a load on the truck . It did ok with our 17 ft Casita , not so well with our 21 ft trailer .
#3 tows far better than #1 or #2 , gets better gas mileage , holds gears better and is much more pleasurable to drive ( towing or non towing)
A standard naturally aspirated 6 cylinder engine and the Ford EcoBoost are two totally different engines in my estimation.