I'd say bigger truck, and don't rule out the Ford 3.5 Ecoboost.
We found a used 2016 with the 3.5L/3.55 and the factory 36 gallon tank and integrated trailer brake. That ran us $27K out the door with 63K miles on it.
We also get 8-10 mpg depending on winds and terrain and a 250-360 mile range depending on where we are towing. That's with 8200 lb trailer according to the scales. You should get better with a lighter trailer.
Driving across Oklahoma and Missouri last week, it stayed in 5th most the time and around 2400 RPM. Once we hit Illinois, it pretty much stayed in 6th and dropped below 2000.
For anyone looking at tow vehicles... get away from the suburbs and start looking at a dealer out in farm country. You'll find more selection.
