I'll admit that I'm more of a mountain backpacker, though in my younger days I did quite a bit of hot weather travel with packs often approaching 100 lbs. And I'll confess to just returning from a short trip with a couple of Pentax 6x7's in the pack, though that was so my
wife wouldn't get impatient with me fiddling with a view camera. If it were my preference, I'd have the 8x10; but I normally just use that for dayhikes. The potential problem with roll film in humid tropical situations is that you have to be conscious not to leave a roll of film in the same for so long that it swells and jams something. I've never had that personally happen, but have heard stories from others. My logic is simple. If I'm going to all the trouble to get somewhere special, I want the highest quality shots that are realistic under those circumstances. I am multi-format, so know the pros and cons of the various options.