I am going to give you a recommendation based not on objective considerations of efficiency and comfort, but fun.
Pentax 6x7 with TTL and any of the nice 2.8 or 2.4 lenses, or a 67II with auto exposure. Big, yes. Heavy, yes. Too
heavy? That's up to you. I would get one overhauled before taking it, and run at least five rolls of test film through it
before the trip. I'd also locate en route labs to keep track of any issues, as a previous poster said. I took one to Alaska
and Puerto Rico in a backpack with a spare lens and supplies. I also had a mechanical self timer to use with mirror lock
up.
The pitchforks and torches should arrive within a few minutes...