We've been to jamboree in the hills twice and to 4 NASCAR races with our airstream so I've been there
Make friends with the water and pumper truck drivers, our neighbour at our first jambo gave the pumper truck driver a generous tip the first day and never had to worry about full tanks. Water was free at jambo. There's always lots of portajohns around and showers for $5.
I'm planing a bachelor party for a friend at either a music festival or a NASCAR race, I'll b bringing my airstream and we'll be renting one or two motorhomes for the weekend. The bathroom in my trailer will be for emergency use only and we'll all take advantage of the facilities in the rented rvs.
There was atleast one company at jambo would rent out various trailers, from popups to sob's. They would deliver the trailer to the campground and set it up for the weekend, pricing was reasonable.