I was up at Horseshoe Meadows road about the same time at Dale. True in what he said about the road. I would suspect that by Monday, the last gate should be open. there is literally no reason for the gate to be closed.
As for rides, I also was at Onion Valley on May 7th.... just hiking around. When I got back to my car, there were close to 10 PCT hikers looking for rides, not into Indepenance but Bishop. There was a shuttle Van there picking up 5 hikers. I made the offer for 2 hikers, but ended up taking 3 down to town where they were going to thumb a ride to Bishop. When we got down to Independance, at the Post Office (one hiker had a package there, but was closed because of Saturday). Across the street there was a PCT hiker thumbing. I made a comment to the hikers in my car, and to my surprise, the hiker across the street was a close friend. Well, I said, today is your luckey day and drove all 4 to Bishop. No I must tell you this, it wasn't easy since my car was already full, and with my dog. They didn't care and off we went.
They intended to catch the Eastern Sierra shuttle on Monday back to Independance and start their hike.
So when do plan on being at Horseshoe Meadows?
I am heading back up on Monday for a week of day hiking.