No idea. I assume it started out as an informal gathering and has picked up on the vibe from similar meets around the country of the same moniker. So really probably just a few people who said, "We should meet," and eventually said where they should meet.
Is coming up this Saturday, I'll be there around 9.
No idea about the silver wagon. My wife swears she saw a white one, but I have my doubts. I can't remember any other GT wagons after thinking about one for the last year or so. I am full of no ideas