I am driving a 2014 5.7 CM Tundra towing a 31BHDD North Trail. I travel North and South from our home in Ashland. While I don't have to deal with the altitudes you will experience I do have to drive over multiple passes to get where I am going.
Here are my numbers from our trip home today:
Front 3,400
Truck 7,200
Rear 3,750
Trailer 7,050
The front weight of the truck is 50lb off the unloaded weight. This load, with 2 kids, 2 dogs, wife and trailer, is exactly at our GVWR of 7,200. This is about as heavy as we will get as we were fully loaded for a 5 day trip.
My impression:
The truck has more than enough power to pull this load. As a matter of fact we could easily pass trucks and RV's struggling on the passes. More than enough power. The suspension felt as though it was feeling the load but there was never any oscillation or questionable moments. The worst was a major dust devil we drove though. I saw the RV in front of us make a big sway and saw the grass and******swirling so I saw it coming. As we went through it it was definitely 2 hands on the wheel.
As far as the descents are concerned, learn to tune your brake controller and they will be a non issue. When we are on the road traveling I increase the brake assist. When we are maneuvering or driving slow in town I decrease it a little bit. That keeps the trailer from locking up at slow speeds.
My opinion on the whole subject?
If you have the towing pkg you should be well within your trucks limits. But you would be wise to drive within your limits. Don't worry about your truck if your maintenance is up to date. Drive within your limits and don't worry about where you go within reason.
Enjoy the ride!