it says closing at 6:30 p.m . but from comments it sounds there is overnight camping. is this so?

Yes there are several first come available spots on the site.

After 630 you can still pull through the campground and if you find an empty spot to call you are allowed to until the morning!

There are overnight camping sites. Most are by reservation through the Santa Barbara parks website. There are some first come, first serve. The sites are $29/night with an $8 fee.

I've gotten there at midnight, found a spot, set up camp, and then paid in the morning for that night and the following week. The park itself doesn't close at 6:30, just the booth up front, and the day parking spots. 😀

Yes there are overnight camping sites there

But only if there are sites available

Yes