Saturday of Labor Day Weekend, there were a few sites available at 3pm. I got what I hope is the least nasty. Bless my van for being tall enough to generate its own shade.
What a cool discovery! You leave Route 160 just a little north of the bridge that takes you to Pittsburg/ Antioch and take a bumpy little road along the edge of Sherman Island. The road follows the southern side of the Sacramento River to the tip of the island, where there is a nice county park for the windsurfers. It's roughly where the Sac River meets the San Joaquin River, and it is a great windsurfing spot.
Close to Lone Pine, really excellent view of Owens Valley south over dry Owens Lake, The last 2 miles have many brutal diagonal speed bumps, beware!
I came here 15 years ago with abalone-diving City friends. I'm not even sure that's a thing any more. Anyway, the campground is still here and it's still awesome. They have spots available when no one else does, and it's the simplest check-in ever: Pay them ($5 off for cash!), they give you a receipt for your windshield and tell you to park at any picnic table/fire ring that's not occupied. The rest of the world seems to get more complicated and bureaucratic, but this is the easiest damn check-in I've ever experienced. Checkout 2pm. Ocean Cove Bar and Grille is a sweaty uphill 3/4 mile walk away. Basic bar food, but great view of the ocean and campground.