Definitely a big camp feel. They don't close the trails until around 10 pm. There is one camp identified as a "family" camp. In all the rest you can pretty much do as you please. I will tell you the camps fill up quickly beginning on Friday night though. You might look into joining one of the clubs that have their own campsites, although that's not supposed to apply on Jambo weekends because the Jamboree is paying for the whole park. I belong to ArkLaTex off-road and we have a camp there. It was new last year and there was almost a mutiny among club members because of the amount of effort put into creating a new campsite out of dense piney woods, and being told we couldn't claim it for ourselves that specific weekend didn't go over very well. But it all worked out in the end.
There are a couple groups out of San Antonio and Austin that make the trip.