I was heavy into Lionel trains about 30 years ago and the TCA (Train Collectors Association) had a HUGE SHOW at York, PA Fairground. Anyone that has been to that show knows what I am talking about! Show used EVERY building at the fairground and you could only rent ONE six foot table per TCA member.
Anyway - my life headed in different directions and I got away from messing with the Lionel stuff about 25 years ago so I don't know what the show is like today but I know it is still pretty big.
Now for the point I want to make about parking lot deals - when the York show was going on people had the idea of doing other shows before the York Show at motel parking lots and stuff. When this started everyone bitched it was going to kill the main show at the fairground but instead the show just kept getting bigger & better. At one point dealing started 4 or 5 days before the "main show" with smaller shows at several motels each day. There was never a shortage of deals or trains. Yes some of the "better stuff" was gone before the main show but plenty of other stuff still ended up at the show.
My point being - parking lot deals will not kill or harm a show as long as enough people bring machines and parts to sell at the main show. One suggestion I have for guys making parking lot deals is to see if they can donate to the show somehow to help the promoters. It cost guys like Ivan (Allentown) and Rich (York) a good bit of time and money to make these shows happen. Yes they make a few bucks running the shows but not enough for the time & effort it takes. So maybe see if they need a hand with anything or walk up and hand them a $10 or $20 bill beyond the admission fee and tell them to use it to make next years show even better. (Knowing both Ivan & Rich pretty well I doubt either would take your money but after all they did provide you with a great meeting place to make a deal so why not say thank you with a little something tossed in their direction.
The most important thing any of us can do is to try to help them have as many machines as possible on the show floor as late as possible the second day. It is kind of discouraging to see half empty halls midway through the second day of any show!
Just my 2 cents on things!