We loved this campground!  There are mature trees between every campsite that provide privacy between sites.  The campground is setup as a bunch of loops with a large common area between the rear of every campsite.  That's the only place you're going to see your neighbors.  It's a perfect setup for a bunch of people camping together at separate sites - get enough of them and you'll have the entire common area between you to spread out!  For us, we used that large open space to setup our Starlink satellite antenna, and that was necessary since Verizon is basically a dead zone in that area.  

The communal showers were nice.  BRING DOLLAR BILLS to change them into tokens for the shower. A couple tokens (one dollar) is enough for a decent shower.  

Your paid campground site gets you day use access to the other nearby parks: San Onofre Bluffs and San Clemente State Beach.

Got an e-bike?  Lots of people had them.  I think as long as you're on the pavement there's no issues but check with the park regulations for any off pavement use which would include the trail to Trestles.

CONS:

The dump site was closed this weekend (8/18-8/20).   But with our day pass we were able to use the dump site at San Clemente State Beach.  NOTE: Day use is up to 10PM and they also have a dump site at the Bluffs.  Just keep in mind you may have to wait in line with other campers checking in to access the other areas.  We went at "dinner time" just before sunset to avoid crowds.

At each bathroom / shower area, there are a set of sinks - one for washing hands and a couple others for (apparently) washing dishes and other stuff.  However, they were turned off.

Overall, this was one of the better campgrounds we've stayed out.  We would defiintely come back here.

• We arrived as the sun was setting and had a glare in the windshield so it was a little tough getting through the tight loop but we made it.  Had we noticed that we were supposed to turn right before the bathrooms, we would not have had to do a u-turn!  That was my mistake.   We had a 22 foot trailer and were just barely able to squeeze through.   Many people had their vehicles parked right along the narrow road in.  I saw larger RVs there - I can only imagine how difficult that just have been to get through.  There's a section of road where if you go off it, you could potentially roll down a hill. 
• Check in for this campground is across the lake at the "bait and tackle shop" (15029 CA-79, Julian, CA 92036) and that's only open until 6PM.  If you arrive later than that, that's OK just check in in the morning.  I wouldn't recommend trying to pull a trailer over to the other side as you'll have a difficult time turning around.  The camp host will remind you as you're entering or leaving that you need that parking pass.
• The best site in this park would be number 23 as it has a clear view of the lake and a very large "front yard".  We were in 21 and had a partial view with the two other sites closer to the lake blocking our view.
• Cell service for Verizon was OK for phone calls, not so great for data.   I noticed driving around the lake that there was 5G in the area, just not at the campground.  Top data speed at the site was around 2 MBps down, 0.5 MBps up.  If you have a directional signal booster, that may help.
• We brought out Starlink dish for internet service.  The trees blocked the satellites every 7 minutes but that was OK for streaming movies.  We never experienced a full outage, just brief moments where the speed went way down.  Our best Starlink speed at the site was 174 MBps down, 11 MBps up, plenty of bandwidth.
• There are two free campground shower on site, bathrooms and a dishwashing area.  A small store near the entrance has a few food items.
• The camp host was courteous and drove around once in a while to check out on everyone.  
• I didn't notice any trash cans on site.  We packed our trash out.
• The nearest town is Julian - about 6 miles away.  It's a nice place for a quick day visit where you'll find gas (including diesel), food, restaurants, historical buildings, etc.  Of course, you should get a pie while you're there!  Julian is well known for that.
• The site was clean and neighbors were courteous.  We had a large group camping a couple spots away but they kept the noise down.
• If you have kids, there's a nice playground by the lake.
• We had a beautiful view of the Milky Way at night, visible to the naked eye.

Overall, I would say this is a great camp area to visit with several recreation opportunities nearby.  We came for mountain biking.  There are plenty of trails to ride.