I've flown over Mammoth enroute to Oakland on a cross country from the
Washington, DC area. I crossed the Sierras near Mammoth at 15,000
feet, and had no desire to do it lower. That area is a relatively
high point in the Sierras -- both north and south are lower terrain.

Why not cross at Tahoe and head south? It would still be a lot faster
than driving. There is a lot to be said for a robust route -- one
that is suable under a variety of weather conditions and that does not
require O2. A longer but even easier route would be to head south and
cross around Palmdale.

Paul