So, after getting a mini experience up on the Atlas, I wanted to customize the displayed image.
Visited my experience.
Positioned the Camera for the shot I wanted
More; Options >> Screenshot
Be sure to check the boxes: Lock aspect mode & Atlas Thumbnail Mode
Then click save to file. I chose my desktop for location.
Then pulled it up in of all things MS-Paint LOL
Added the Text I wanted.. then saved it as a PNG file.
THEN. MY PROJECTS >> more options >> Edit Atlas info
Uploaded the file and save
Voila !
dumb simple new thumbnail for my Atlas listing !
I am sure you have better tools than MS-Paint, but this was proof of concept...
Be sure to save in the same aspect ratio, of the atlas edit reject the file !
-Enjoy !