I wouldn't worry about theft. Too many bikes to steal, too difficult to take them anywhere. And you need a pass to get within a mile of the venue. I brought my bike last year, but I was camping. Rode it around town for errands and fun.
I heard about a couple people having their bikes stolen around the camp site. I would find a gate to lock it to so you at least won't get the drunks accidentally confusing bikes and riding off on yours.
Parking and locking your bike won't be the problem, it will be navigating your bike through crowded, sandy pedestrian walkways and congested parking lots as GV has yet to address making a bike-only pathway somewhere.