OK fellow geezers:
I'm more or less happy with where my lifts stand for the moment, but I have a high altitude fishing trip coming up in about eight weeks. The altitude is around 6,500 feet and on some days we might hike out five or six miles, mostly over trails, although there's some fairly rough terrain. We try to move pretty quickly (more time spent hiking means less time fishing). There's less pressure to move fast on the way back, but of course the beer and whisky are calling, so we end up moving pretty quickly anyway.
I don't have to carry much beyond my fishing gear and a light pack. Last year, I didn't have any problem making the hikes, but I was definitely slower than I'd like to be. I'd like to be faster and we might try to go farther and higher, depending on weather conditions and where the bigger fish are hanging out.
How would you train for this? I'd like to improve my ability to hike at high altitude at a pace around 15 minutes per mile. I live at low altitude in a flat country, but do have a treadmill at home. I'm not planning to do this on a permanent basis, I just want to improve as efficiently as possible. After the trip, my focus will be on lifting again.