This is a tough question. I'm a hiker, which is my passion outside of photography (which is work). I prefer to go as light as possible, mostly because at my age I need that. So for me, a P+S is fine, and a mirrorless is a luxury. But I am not hiking to take photos.
So here's my question: what is the primary purpose of this trip? If it's photography, then by all means take the D800 and the tripod and the lenses. (That 70-200 would be key for a lot of landscapes, at least the way I like to shoot.) If the purpose is the hiking part, and the photos are just to document that, then I would take a smaller camera.
Making good photos -- good enough to justify carrying the gear -- is a time consuming project, *and* you need to be in the right spot at the right light. That may mean stopping very early in the day if you find a good photo opportunity but need to wait for evening light. It may mean spending several hours in one place shooting wildflowers, or waiting for the sun to illuminate the peak reflected in the small glacial lake. All of those things are wonderful, but if you have to make miles for any reason, they will prevent you from doing so.
There is no one right answer. I hope you have an amazing trip. (Also, having pack animals bring you beer is the greatest idea ever.)