Sorry about my slow response. I just saw this today.
I pull a 5.0TA Escape with my 2007 Frontier 2WD Crew Cab 6cyl. The biggest problem we had with this combo was getting someone to install a 5th wheel hitch in it because no maker makes rails for the Frontier. After several refusals by installers, I got one to call the place in Chilliwack that installs hitches for Escape and they convinced him it could be done. Escape doesn't really recommend towing with a midsize pickup, but I had been towing a Scamp 19 (about 1,000 lbs lighter than 5.0) with ours. I talked to Alf (EscapeArtist) who also pulls with an Frontier and went to check out his setup. He had been doing it for quite a while against the advice of his Nissan dealer in Ontario and raved about it.
We've towed the 5.0 through the hills of TN and VA and spent 6-weeks last fall in Newfoundland, which is pretty hilly. We keep our speed under 60 for safety and gas mileage (16-17mpg), but can go as fast as needed to pass etc. We don't pass too many others on steep hills, but I don't feel we block traffic. We try to not load heavy items in the front of the trailer to keep down the hitch weight.