Dealer trade stands

Hi, not sure whether you're looking for photos from Britain or the US, but I've come across a few newspaper photos of A-C dealerships and also if I recall from the Royal Agricultural Show, Royal Highland Show and so forth by searching the British Newspaper Archive.  You need a paid subscription but I was able to browse it for free at my local library - https://www.britishnewspaperarchive.com/

I think the Museum of English Rural Life in Reading has some A-C material, might be worth asking them as well.