Hi there WPMUDEV.
I don’t know if this is quite in your spec but it kind of involves Smush, so I thought it might be worth a try.
Images that have been Smushed apparently ( according to the developer of “No Right Click Images Plugin” ) sit outside of WordPress ( “If you are able to click on an image to display the image in a new window, it is then outside of WordPress and can’t be protected.” – their words ).
I need some way of preventing images from being right clicked to prevent them from being easily saved (for the technical illiterate) but it still needs to work with the WordPress Gallery Magnific lightbox.
Any ideas/assistance will be much appreciated.