The dirt road to the stocker trailhead is fine. From there to the hiker trailhead is rough - but I've regularly seen 2WD vehicles there. I'm not exactly sure, but I think it's about 5 miles from the hiker trailhead to Onion Valley road - where hitching should be easy. Getting from the traihead to the road may require hoofing it, since the only traffi will be hikers exiting Shepherd.