Getting a shuttle to Horseshoe meadows (Cottonwood, New Army or Army pass) or Onion valley (Kearsarge pass) is completely routine.
There's a handful of people in Lone Pine that provide rides to different trailheads. Rather than post some names/numbers here, just search around a bit or call some of the local outfitters for suggestions.
I'm not certain what the parking situation will be like @ the Portal this upcoming summer. Even if it's sorted out, I still think just leaving a car in Lone Pine is easier than parking @ WP. Getting a hitch back down is maybe the easiest thing to do in the world.
3-4 days is a good schedule. Also, the beauty of going in the back door is that you can get a walk-up exit permit ie you don't have to wait for a cancellation or deal with the lottery. If you're solo, even better; I've never been shut out.
Without having to deal with pre-planning or advance permits, you can pick & choose the absolutely best weather window. If you see a forecast for building high pressure over the Great basin, with expected clear skies for 4-5 days, then that's to time to jump in the saddle and go.
Last edited by Hobbes; 12/09/16 03:22 PM.