Hey, gratz on the acceptance! I'm in for whatever. But realize you will be smothering hot and filthy most of the day Saturday...just comes with the territory (they do have a gigantic water fountain kind of like you see at kids' water parks, so you can cool off.) But don't plan on wearing anything you want to keep in pristine condition, or even that you can't take off.
Honestly, I usually wear a tank top and a lot of sunscreen. Even a tshirt has been too hot, some years.
Come to think of it, maybe that's why people love Bonnaroo so much...where else can you play in the mud and a giant water fountain without people thinking you were certifiable?