any reason you don't resupply at the usual locations? Bishop Pass is a massive detour, Kearsarge Pass is pretty off trail as well if you actually hike down to Onion Valley (where you can have food at the pack station for a fee).
The common resupply locations are Tuolumne Meadows store and post office (send to self, general delivery, hold until expected arrival date). Then at Reds Meadow resort (mail to them, they bring it down). Vermillion Resort at Lake T Edison and Muir Trail Ranch are the final two standard resupply locations. Most hike from the Muir Ranch without any further resupply.
detailed info on all these here (top right of the page):
http://didnt.doit.wisc.edu/outdoor/Muir2009/information_links/information_links.htmpackers are not a good way to resupply, because not only are they expensive, you do have to meet them to receive your goods. If you don't get to the location as planned, they pack it out again. They cannot leave the food on the trail.
Most who don't want to carry all food from Muir Ranch to Whitney hike out at Kearsarge Pass and hitch a ride to Independence, where you can buy food or pick up a package you mailed to yourself at the post office. you lose more than a day, and at least I feel exiting the wilderness and having to re-enter spoils the whole JMT experience.
