How many hours before the show will they allow you to enter and Park for tailgating.

The park generally opens ONE HOUR before the event.

I have seen overnight campers in some concerts from the night before. Even equiped with portable swimming pools.

Yes, you can tail gate.

The park generally opens one hour before the event. But you can be in the parking lot for the tail gate parties long before

I'm not quite sure but I've been to tailgating party there that started 4 hours before the show