I resupplied via post office at Tolumne Meadows and Mammouth then a 11 day resupply at Muir Trail ranch. I used the Bearicade expedition and I was able to pack 11 days of food into it, I actually only needed 9 days to make it from Muir Trail Ranch to Whitney Portal. If I hike the trail again, which I likely will, I will skip the Tolumne resupply and carry enough food out of Happy Isles to make it to Reds Meadow, from which its an easy trip via shuttle and bus to Mammouth.
The 11 days of food out of Muir was a bit heavy but I was very glad that I did not have to leave the trail at Kearsage to hitch into and out of Independance as most hikers did.
I hiked in July, the mosquitos were quite active and if I had the choice I would hike later in the Summer.
I did not have the logistics of public transport to contend with as my wife drove me to the Happy Isles trailhead. Hikers I met toward the end of the hike offered me a ride to the bay area which saved my wife quite a drive.
A hitch would be needed from the portal to Lone Pine, there is a bus fom there to Mammouth. A YARTS bus goes from Mammouth to Yosemite Valley then another from the Valley to Merced and the Amtrac station. These buses require an overnight stay at Mammouth as the Crest bus arrives in Mammouth after the YARTS bus to Yosemite valley has long gone.
You are in for a real treat, the JMT is magnificent!
Richardd