The "trailhead" is just a switchback on the road, where the Forest Service closed off an old road and is trying to restore it. Decent trail into the basin following this disused road, but a lot of water crossings. After the road ends in the basin, I had a ton of willowbashing to contend with, and it was an absolute suck fest. Once through the willows, easy to get to the saddle between Hoosier Ridge and Red Mtn C. Because of the willows, I decided to add ~100 feet of gain by going over Red Peak A (unranked summit, different from Red Mtn C) and descended its East ridge to another disued 4WD road, and followed that back to my car. Made a nice loop.
The road was rough in spots, but mostly a pretty easy drive. A Forester might be able to do it without too much difficulty. Only room for one car at the switchback where the old road up Pennsylvania Creek starts, room for 2-3 more at the next switchback up. Nice camping along the road.