I have scratched the surface of studying Dealer Display Layouts. My answer is there were no factory layouts for pre-war.
The Dealer Display Layout were a "new" marketing idea and approach to increase sales in the retail stores in the '50's.
email forum member jagrick and you could contact Bob Osterhoff at trainpaper.com.
A guess would be that some stores may have set up their own loop in a window.
First paragraph and this a few store window photos
You get the idea-the display to sell trains was developing.