[sualfred]

That was my first thought, but that means I have to create a large amount of hidden lists for the library + home window. This will cause a speed and loading penalty.
The best way would be to have an python script, which gathers those images and stores them somewhere physically.

//Edit
Correction -> Kodi should be able to display thumbs of folder contents That would be the best way to handle it. Maybe in the future.. someday.