I did a spot check on campsite availability, since the Rally is a little over 4 months away, July 10-16. I only checked on the weekend of July14-16, since people sometimes camp for only part of it. (I figured the weekend was most likely to be reserved the most at this point.)
It looks like there are a dozen and half or so sites available, plus the FCFS ones. There are quite a few of those, over two dozen. Here's the link again for the reservation site: https://www.recreation.gov/camping/vallecito-campground/r/campgroundDetails.do?contractCode=NRSO&parkId=79060
It looks like there are a dozen and half or so sites available, plus the FCFS ones. There are quite a few of those, over two dozen. Here's the link again for the reservation site: https://www.recreation.gov/camping/vallecito-campground/r/campgroundDetails.do?contractCode=NRSO&parkId=79060