Automatically insert featured image where none exist?

Hello,

Is there a plugin that will add a random image to a post as a featured image but that will only add an image if none already exists?

So if I post 12 articles – 5 of them with featured images – I’d want this plugin to randomly assign, from a media library, a featured image to the other 7 posts.

Preferably without duplicating images already in use for that day. Possibly it can pick the image in order until it runs through all the images in that library one time?

I’ve just spend hours trying tons of plugins and not one even came close. There are those that will allow me to manually import an image – but I want it done automaticaclly to every post that doesn’t have an image already assigned to it.

Thanks!
Rob