I am the owner and operator of East Side Sierra Shuttle. I live in Independence. I will try and answer your questions. You don't state your date(s), but June to October 5 say, it's pretty easy to hitch to town from Onion or to hitch back up in daylight hours. I have lived here for 17+ years and I have never seen anyone get stranded yet.
Most cell phones work at Kearsarge Pass and also at Onion Valley. There is plenty of room in the bear boxes at OV. I have never heard of any security problems there whatsoever. I haven't tried it yet, but I often joke that a person could put an unwrapped box of Whitman chocolates in one of those bear boxes and as long as it had someone's name on it and was dated, I think it would stay there, unmolested, all year. The people who do long distance hiking are a pretty special group of very nice and honest people who respect other people's property. As are the people who live in this remote little village in the desert.
The Kings/Sequoia Pack Station is 150-200 feet from the trailhead.
No one is allowed to cache at the bear boxes at Charlotte Lake. There is limited space and because of the popularity of the Rae Lakes loop hike cacheing is banned at Charlotte Lake. Your box would be disposed of by the Park Service.
If you have further questions please call me at 760-878-8047 or email me off list at paul@... .
I am planning on a NOBO hike beginning at Horseshoe Meadows going over New Army Pass on 7/27 with a side trip to climb Whitney. This will necessitate a resupply at OV or Independence. Cost aside, I have to agree with Ravi about the difficulty of coordinating with a pack train since my hiking rate varies a lot with my conditioning from one year to the next, When I would arrive at the Charlotte Lake jct after 75-80 miles over NA Pass and Whitney is wildly uncertain.
My questions are: 1) How hard is it to hitch to Independence from OV? 2) Is there cell phone reception at OV so I can call Paul F or Mt. Williamson for a ride to Independence? 3) How far is it from the OV TH to the Sequoia Kings packers? 4) Is it illegal to cache a spare bear canister near the Charlotte Lake jct that I pack in before my hike which is not in a bear box?
I do not begrudge the S-K packers ability to make a profit, but $120 to retrieve a package from the post office and hold it for a few days does sound a bit excessive even if it does include a shower. I may do that anyway if in fact it could take several hours or more to get a ride from OV to Independence and back up and there is no ability to call for a ride. I considered caching at OV but that does not sound like it would be totally secure. Certainly if a high percentage of JMT thru-hikers did it the bear boxes would not have sufficient capacity.