Deano,
Welcom to the world of car shows and idiots. I quit taking mine to any shows a few years ago because of the fools that climb on them. I walked off once for a few minutes and came back and two teen agers were sitting in the car. By the time the cops got there both were more than happy to be escorted off the grounds. A friend of mine who is really into shows had his there and some would be cowboy with one of the big belt buckles walked over and leaned way over his door. The belt buckle took off a chunk of his custom paint about the size of a half dollar. It is fortunate that I had my gun with me at the time or there would have been a real problem as my friend was looking for it As for the questions, no matter what size sign you put up, people are still going to ask if it is real. I just politely explain that it is not a Shelby Cobra, that it is a replica and in no way is it original. Most people are polite and I don't mind their questions, but you are always going to have the jerks at any car show no matter what size the show is.
Ron