A little awkward start to the night/day, but still a great show. Indeed, they started going in at 11pm. Trailers filled the grass parking lot and they did a pretty decent job lining everyone up there for staging.
We met with several people in the grass lot 7-8ish, then headed back into town until we got a text saying that they were letting trailers in. Walked around the show until 5am or so, then slept in the van or a couple of hours before going back in just before the sun came up. We were done early enough, by 10-ish that we went and spent the day @ Gettysburg with our oldest son as tour guide. Currently doing some college visits with him in PA.
I can't speak for all of the vendors, but those that I did, were all very happy with their sales. I know Mr. Dover & company were busy the entire time we were there. It seemed like all the karting guys were pretty much giving stuff (literally) away by 8am Saturday wanting to go home. We definitely picked up some deals.
If you own an open wheel racer (karts, mini sprints, sprint cars, etc.) this is the show to be at for sure, no matter what time they let you in.