You won't see an improvement in MPG when towing. In order to overcome drag, your engine has to produce power. In order to produce power, it has to spin the turbos up to get more air. More air means it's going to use more gas. No tuner will change that enough to justify cost.
Now, if you want to adjust shift points, get more power at certain times, or wake your engine up and make it perform better than it does with the factory settings, sure. Go for it.
2019 Rockwood Mini Lite 2509S
2018 F-150 XLT FX4 Crew Cab 3.5EB 3.55
Equal-i-zer E4 hitch 1,000lb bars
nights camped 2019: 42. Miles towed: 4500.
2020: 30 1500