Yes, I know this is a long way away, and at this point I am just thinking about staying here the third week in May. I was here last April, but it turned out to be in the middle of spring break, so the zoo was packed and several other places were swamped with people. Plus the rental car people wanted to charge a huge premium for spring break week!
Right now, obviously, there are lots of spaces available, but they will get booked fast in early winter. There are two campgrounds at Sweetwater. The lower campground is partial hookups and cost $29 per night. (There are corrals in this area, and there might be horses, so if you don't like the smells, you might not want to be there. The upper sites are full hookups and cost $33 per night. I know that is expensive compared to a lot of places, but it is reasonable for California campgrounds. And the upper sites are on the top of a fairly high hill so the campground has a 360 degree view and wonderful breezes coming all the way from the ocean. Sites up there are huge and have a lot of greenery between them. No shade, however.
Check the first photo of one my upper site on my blog: http://grandmajjb.blogspot.com/2016/03/ ... go-ca.html