A variation of your Plan B with some other options:
7/17: Leave SF at 7pm and drive to sleep at Tioga Lakes or Touloume meadow in Yosimite (that is 8k-9k ft)
7/18: Hike Mt. Dana (13k) or Mt. Dana area (Gaylor Peak??, Saddlebag Lake??). Get to Horseshoe Meadows (9.5k) campground and spend the night.
7/19: (EASY)Hike in the Horseshoe Meadows area (10K+). Get permits, spend night at Whitney Portal campground.
7/20: The big day, leave campsite at 2am.
Horseshoe Meadows could be substituted with Little Lakes Vally/Mosiquito Flat (
photos here ).
