Hopefully this won't come across like I'm being a dick about this whole thing but there are a few more things to think about. The stuff you're talking about is fine and I think it sounds like a lot of fun and I'd show up, but you need to be careful in a few areas.
First off you should probably look into some type of liability insurance or make up some type of waiver that EVERYONE has to sign before getting in. Especially if you are opening this up to the general public. If it was just a bunch of us RME guys I don't think any of us would care if something happened, but when you get a bunch of high school kids showing up in their dad's Exploder and want to ramp the thing and it ends up on its side or they drive over some kids leg, be prepared for the dad to come back sue the organizer or even East High since its on thier property. I know it sounds lame, but it can happen. With something like this its really important to cover your a$$ just so you don't have to deal with idiots coming after you cuz they scratched their paint trying drive a tire up on someone elses truck during a dog pile.
It's well worth the time to prepare a good comprehensive waiver of some sort that clears you as the organizer and East High of any responsibility if any gets hurt or any trucks get damaged.
Just a thought. Still sounds like a good time.