The guest list is the best idea.
As far as throwing people out. It probably won't come to that (I hope) but if it did get out of hand, I know a few guys who will be on shift in the park that day. They've had to toss people before. I've made our intentions clear to them, and that anyone being obcessively noisy and or obnoxious they can feel free to give the boot.
All people have to understand is that its a meet. Not Race Wars. We can let anyone in, but we should maybe hand out little Top Tier welcoming cards that say hey, welcome, enjoy your stay, thanks for attending blah blah but please be respectful of the group and others in the park.