If you have a nice wagon you'd like to display at the Hershey museum, here's your chance: http://www.aacamuseum.org/family-affair-station-wagons/
Where does it say it's too late? That AACA web page lists the cars they would like to get. I don't see any mention that it's too late to submit a car, and, with the display not starting until May, there appears to be plenty of time to do so.