Superchip Flashpaq tuner for Ford F350?

Thanks for all of the input! I bought my truck off my Dad, and it just rolled 200K miles. I know it's been well maintained, but when I tow I don't feel like I'm getting the power out of the engine that I should. The turbo doesn't kick on when I'm putting an extra load on the engine (climbing a grade) but will kick on when I'm just driving down the highway. In 5th gear, I will lose 15 MPH on a 4% grade (70 to 55) pulling my trailer (5100 lbs dry weight, maybe 5700 fully loaded). Running without the trailer, the truck averages 19 MPG at 80 MPH, but that drops to 11 MPG pulling at 60 MPH as soon as I hitch. I initially blamed aerodynamics (this is my first trailer, and the fact it sits so high and is a bumper tow gives me the aerodynamics of a barn door), but now I'm wondering if that's the issue at all!