Lots of options
So the campground site listed here is not a specific campground but Mt. Tam park which contains several different areas where you can camp. While in the area we hiked a couple of different trails and visited the Pantoll campground which was a great option. My best suggestion if you have a half day (and hike fast) is to do the Matt Davis to Steep Ravine loop that gives you amazing overlooks of the ocean along with beautiful redwoods. The hike was strenuous and well worth it. If I had more time in the area I would have stayed at all the different campgrounds this park has to offer.
Month of VisitJuly