The For Sale corrall is $10 for the weekend (you can park it there Friday afternoon and leave it as long as necessary). Yes, you can leave it on the trailer. Due to limited space and to keep down traffic inside the fenced area, we moved the For Sale area outside the fence a couple of years ago. This seems to work out much better for everyone. The only downside to this is it's outside the fence. It is a city park and the East Ridge police patrols it regularly. If any of the hundreds of folks there during the night spot any suspicious activity, we'll be on top of it. We've had 4 all-weekend shows with For Sale corrals and, to my knowledge, no one has ever complained about anyone messing with an unattended car.
With that said, to cover us legally, it's still a "leave it unattended at your own risk" deal. I would suggest that even though it should be OK unsecured, it would be a good idea to chain and lock the car to the trailer and lock the trailer hitch.
If you don't make it the meeting tonight, see you at the show!