It's been a while since I discovered this and I can't test it right now. But when I tried to point at a directory with read only permissions it failed to load any wallpapers. I also tried to mount to a subdirectory and it still failed. It only worked with rw permissions, which I do not want.
I think you must be confusing this module with another one, my module loads images from remote sources (bing, reddit, icloud, etc), not a local directory.
It's been a while since I discovered this and I can't test it right now. But when I tried to point at a directory with read only permissions it failed to load any wallpapers. I also tried to mount to a subdirectory and it still failed. It only worked with rw permissions, which I do not want.