I was thrilled to secure a permit beginning mid August from Happy Isles to Whitney Portal. My plan was to do the 220 miles in 14 hiking days, ~15-16mi/day. That sounded doable as long as I condition well in advance and have a pack weight of less than 30lbs (base weight is about 14lbs for this trip). Coming from the flat Midwest means that I would not have very many ways to experience long days at altitude until I get there.
This all sounded OK until my potential hiking partner, whom is in much better hiking shape than I, has grown concerns from speaking with other JMT hikers. His friends, experienced long distance thru-hikers, say that the JMT is a real kicker and was very difficult in the three weeks they did it in last year in August/September averaging 12mi/day and suggest we take 28 days ourselves. I have no idea if they are lightweight or heavy haulers.
Given this, I know 28 days would be more enjoyable but really don't have that much time to do it in. I keep reading around here guys doing it in 10 to 14 hiking days with lighter gear and assumed I could do the same with some training. Anyone have experience with this?

