Just get out there!
I love Oak Grove Campground! We were there for the full moon last month and even though it rained in the morning as we packed up me and my motorcycle camping friends had a blast sitting around the campfire and enjoying peace and the Darkness, that comes with being this far away from the city. I camp at Oak Grove at least twice a year sometimes up to six times a year and if never made a reservation due to its under-utilized situation. Don't tell anyone. It's our little secret. It's very handy if you want to section hike that part of the Pacific Crest Trail and there are also great off road truck trails and dual sport motorcycle trails nearby. One of the loops there has flush toilets and one of the loops has pit toilets. The cool thing is though, the one with pit toilets also has big awesome grills you can actually use a flat top in addition to the grilling portion. So, I like Oak Grove. A lot. I'd also like to give a shout out to Rick the campground host. He's been there for about 10 years and he's always super helpful and very friendly.