I try to travel light at the big events, mostly because getting your vehicle to where you are camped can be a major PITA. Everyone else and their dog are all trying to get in and out on the same little dusty or muddy road, and too many folks don't stop to think about anyone but themselves. For me, the idea is to be able to get to the highway as quickly as possible. I'm hot, tired. grumpy, and about willing to commit felony for that first Big Gulp!
-Bring extra TP in an airtight bag and keep it hidden in your knapsack! It won't hurt if you don't need it, but on the other hand...
-These sorts of events are good to practice your campaign-style camping. Leave the cooler at home, eat foods that don't require a lot of preparation, a gum blanket under you and another one to act as a shebang are about all you need for shelter if you're a little creative. You might also sneak in some bug spray and crotch powder in the same place you hide your TP.
-Start drinking a lot of water two weeks before the event. Being pre-hydrated doesn't make any logical sense to me, but I tell ya' it really works.
-Have at least a quart of water in your car for when you leave. It'll be warm, but it'll help to get you rehydrated quicker. Then stop at the 1st convenience store you pass and buy something cold.
You specifically mentioned going to one of the G'Burg events, but this advice, and that offered by other posters, works just as well at any big National.
Good luck, and have fun!