Tomas: This won't help you in the contest, but you may want to suggest it to the GRL gang....
Instead of LED signs and lots of wires, put the 14-segment displays on the backs of jackets, using EL wire, powered by batteries, uniquely labeled with a QR code patch on the front (where it's harder to see mid-demo), and control it though an iPhone app. Once enough of these are floating around, you could do impromptu flash-mob signage.