Source: Andrew Wilson AKA The Librarian
The ad (attached) appeared on May 31, 1946 and the DIT, simply named "Drive-In Theater" opened on June 7, 1946!! That is more than two months before the Dort opened in Flint (8/29/1946), making this DIT the third to open in Michigan!!! The article is correct, it was "short lived," it closed on 8/31/1946.
No ads could be located for 1947 or 1948. The Starlight apparently opened 7/8/1949. Unfortunately there were no photos. The book was made with the help of the Saugatuck-Douglas Historical Society which says they have over 2000 photos of the area and they can make "Digital Photo Prints" of any photo in the collection. Maybe they have some DIT pix.