Hike out of kearsarge pass and there is a pack station there in onion valley. They will hold your package but it's pricey, that is what I did last year on the jmt. also heard the food mart in independence will hold your package for cheap, you will have to hitch hike down there. There is not much to buy there at the food mart, the guy I was with that resupplied there did not have that great of food.
