How much frontal area does the trailer have?
How fast are you towing?
I get about 12mph towing my boat with my 2016 3.5EcoBoost. The boat is 8ft high and 8ft wide. Not as heavy but the wind drag is the most important element for fuel economy. My brother tows a similar rig with his 2017 2.7Ecoboost and gets quite a bit better fuel economy than I do.
I get 8.5mpg towing an 11,000lb equipment trailer.
You should be doing better with the newer tech and the 10 speed transmission.
My experience with a diesel is that it gave about 30% better fuel economy pulling my equipment trailer.