I towed. a Ranger with the 305 hp V-10 in a 13,000 pound C. When I turn left out of my street, towards the CG I'm accelerating from 0-30 mph on a 8% grade. It stays in first gear longer towing, but I'm up to 30 mph by the top of the hill, towing or not. If you can accelerate on a 8% grade, you can cruise just about any highway grade you will encounter. You might not climb it as fast as a Corvette or even a V6 SUV or minivan, but you'll climb it a whole lot faster than a 80,000 truck.
I'm now towing a Honda Fit, about 900 pounds lighter than the Ranger. I can still feel the load on acceleration. It is a little less, not that much less, I still know I'm towing. On level ground, I can still accelerate as fast or faster than most of the folks in rural Oklahoma or rural Kansas choose to accelerate. I probably couldn't keep up with the stoplight drag races in the northern suburbs of Detroit.