Stayed here in mid-August and really enjoyed it. Better than the San Clemente campground, which is technically closer to the water but not a surfable beach. San Mateo had larger campsites with trees for privacy and shade in between sites. Closest drive to San Onofre State Beach for surfing, and the $30 you paid for a campsite waives the $15 parking fee at the beach! There are no grills, only firepits, so we brought a spare oven rack which made for a perfect grill. It's also a dog-friendly campground, so our pooch had plenty of company. (San O beach also allows dogs, on leash.) Other reviews complain about squirrels -- bring your dog! We never saw one in our site. The only complaints: they don't have separate areas for RVs and tents. We were lucky the campers near us did not have noisy ambience-destroying generators, but one was setting up just as we were leaving. And we heard some pretty loud artillery fire, and what sounded like bombs and helicopters both nights, up until midnight. I know it's next to Camp Pendleton, but geez... is this common at this campground? Also, people unlucky enough to have sites on the outside loop facing east had their view of what would otherwise be open space ruined by nighttime lights from the base.
Also, in response to some other posts here; we felt safe, like the other campers were good company. Regular families, lots of surfers. No creepy types. But there was one site with loud drunks which fortunately was far from us. Unfortunately, you can't choose your neighbors.
