With a 3.73:1 ratio, the 4.30 will have about 15% more RPM's for a given road speed. So say you currently have 2,000 RPM at 60 in a certain gear, the 4.30 will have about 2,400 RPM in that same gear and the same speed.
The Ecoboost gets great mileage because the displacement is small, and this causes there to be much lower internal friction. This is due to smaller stroke length, less piston diameter, so the rings have less wear. Also the lower engine RPM helps boost the MPG. Turbocharging helps boost the MPG too.
The F-150 has about 2,500 - 3,000 cargo rating, depending on it's option level, and curb weight. This is nearly as much weight capacity as the F-250. The F-350 has about 3,500 - 4,000 cargo rating.
Your F-150 can tow the trailer, make sure that you are using the recommended 92 octane gas. If you have a need to carry a lot more weight, such as firewood, generator, or ect. then the F-350 is the way to go. I would still recomend a 3.73:1 rear axle ratio. This will offer better mileage. If you want more power, just press the right foot down, the truck will downshift, and give you all the power you want, even if it means going to 2nd gear and making 330 HP and high torque.
With the 4.30:1 gear ratio, then you will need to be going much slower road speed to reach second gear while climbing a hill. With the 3.73, I can run in second gear at 45 MPH. But of course you get better MPG by leaving it in drive and running a lower engine RPM.
Fred.
