Going up, you'll work the engine and spend the entire climb in boost. I doubt power will be an issue, but wear might be in the distant future if you tow often enough.
Going down I expect you'll be working the brakes because I don't imagine that engine/trans will offer enough hold back for the truck and 4500lb trailer to be of much use. Sounds like you might be setting yourself up for some white knuckle descents, but I've never tried that combination and I doubt many others here have.
I know my old Ecoboost 3.5 struggled to hold speed coming down 7-8% grades with a ~6K trailer, or at least scream doing it and still required some assistance. Your smaller engine will be notably less effective.
