We found a guy listed on the US forest service website that provides hiker transportation. $70 got us a ride from Shepherd pass trailhead to Onion Valley. From there we collected the other car at Whitney Portal.
It was a remarkable trip. We went 48 hours without a single another person, and we saw 5 other people on our whole journey. We found solitude.
I could barely walk. My calves and quads were aching. The switchbacks the day before were killer. Here's our actual GPS tracks: