Bob is right (as he usually is :)), it is a rear view camera used to keep an eye on the trailer. It was the trailer that originally caught my eye, as we were walking by I overheard someone saying that the owner built the trailer from scratch. The workmanship on the trailer was outstanding and when I noticed what looked like a pickup bed stuffed in the trunk of the coupe I naturally assumed he had worked his magic there as well. It wasn't until that fall when I saw it again at the Tampa Nats that I learned it was built that way at the factory by Chevy.
Mike