Beware coming here with anything other than a tent! All sites have a nice level tent pad area.
We camped two nights at Fremont Peak State Park with our pop-up tent trailer. We stayed in Valley View site #2 and were lucky that the paved driveway levelled out at the top (mostly). Some people came to site #3 with a camper van and ended up leaving because they were at such a sharp angle.
It was not clear from reading other reviews or the park website, but this campground has plenty of potable water spigots around all the sites. We found the vault toilets clean and well maintained. Although dogs are not allowed on the trails, there is a service road up to the communication tower that you can hike part way on.
We observed the carpet of valley fog below us in the mornings and evenings, while mid-day you can see out to Moss Landing. We also got to enjoy one of the Fremont Peak Observatory Association (https://fpoa.net/) programs which was amazing! The views of the stars and the Milky Way are unbelievable and the volunteers were awesome.