I always carry a u-lock and a cable (sans lock) which is designed to loop onto the u-lock. I put the u-lock around frame and one wheel (usually rear, but since I have a generator hub, I should put it around the front) and then loop the cable trough the frame and other wheel, then put the ends of the cable onto the U-lock.

As for security - sometimes larger events contract for bike parking, which often comes with perimeter security. You should inquire about whether your event is doing that.