I wouldn’t want the added initial cost, maintenance, and fuel costs of a diesel for towing something that size. If you feel comfortable with the braking and handling of your current half ton then an Ecoboost might be a good fit. They are a powerhouse and pull more like a diesel due to making power low in the rpm band. Fuel mileage takes a hit towing with them, but I’d guess it’s not going to be worse than your 5.4.
If you get the feeling the trailer is walking you around or braking leaves something to be desired it may be time to look at a gas 3/4 ton. Ford’s 6.2 and GM’s 6.0 are both proven long lasting engines with more power and better trannys than your current rig. Mileage unloaded will probably be comparable to what you have but they’ll feel like a racehorse in comparison.
