I ran a search on this forum for availability of FCFS campsites north of yosemite valley, and looks like the main response is "get there early". What time is "early"?
In summer, is it really THAT unlikely to be able to drive to one of the 4 or 5 campgrounds along Tioga Pass and find a campsite on a Friday? I would be coming from the Bay Area, so making the 4 1/2 hour drive to T. Meadows area would not allow me to get there THAT early.
What about driving in on a Thursday afternoon/evening? Would my chances improve then?