Onion Valley to Road's End is simple, by comparison.
The last time that I did this, we had a good organization. First, three strong hikers drove to Road's End and left their car there. They hiked up and over to Onion Valley on Day 1. I was part of a team of four, and we drove to Onion Valley on Day 1. The team of three showed up on foot just after sunset. Early on Day 2, the team of three drove our vehicle home from Onion Valley, and the team of four went up and over Kearsarge, ending up at Road's End around sunset, so we drove the first vehicle home that night. Obviously, going eastbound is a lot more work than going westbound, so you can divide up your group appropriately. You don't want to wait too late in the season to do this. September is good. Early October is good. By November, there is risk from a storm closing the passes for vehicles, and hiking could get problematic.