We tow our 19' Bambi with an 03 Pathfinder. I believe its towing capacity and specs will be considerably below yours. We have over 50,000 KM on the towing combination - our home base is Ontario and the perimeter of our travels includes Vermont, Maine, Newfoundland, Alberta, Wyoming, Colorado, Nevada, New Mexico and Tenessee.
In hill country we've never felt the need to worry about maintaining speed on a grade - on a long, steep grades we've slowed down, geared down - and let the transmission to do its work comfortably. Downhill is the same - slow and easy.
Having said that - over time we've had some mixed opinions on the Pathfinders capability and eventually evolved from a basic WD hitch to a Hensley. The discomfort, prior to a Henslyey, was exclusively heavy truck traffic on interstates.
The Pathfinders weight capacity is 5,000 lbs and our loaded towing weight revolves around 4,200 lbs. Presuming you are towing within your weight capacities, but given your short wheelbase, I believe you might also go through the same learning curve that we have. Although the Pathfinders handling characteristics seemed "OK" we graduated to "Great" once we linked the two with a Hensley - the difference is unbelievable - and I can't emphasize that enough.
Bottom line is that our rig today seems well matched with the Hensley and we have no hesitation in considering any trip - anywhere - the only limiting factor may be the Pathfinders age and mileage - we now have almost 200,000 KM on it - and we're wondering whether it might be time to trade. We did plan on moving up to a larger vehicle when that time came - but given the economics of the day - we'll be quite happy to buy back into the same class and size of vehicle as the Pathfinder. The vehicles that we are considering are another Nissan Pathfinder, a Nissan Frontier or a Toyota Tacoma - all smaller than yours.
Bambi - 2002 (The Toaster)
Pathfinder - 2009 (The Buggy)
"I'm not young enough to know everything ....."