Using a WP Network site to Manage Images and Finding a Blank theme

I’m testing using a site on a network to serve up images to the rest of the network sites.

I’m doing this because we use a lot of the same images across the network and rather than having 20 different variations of media galleries and duplicating image uploads into each one, it would be easier just to run images from one site and use the ‘Insert from URL’ command when adding media to specific posts and pages across the network.

This looks like it could work out ok. One issue I want to solve is how to prevent the public from viewing the images site directly whilst still allowing for the images to be served across the network. If I set the privacy on the images site to anything other than open for public, then the images won’t serve to the network.

One idea is to have a ‘blank’ theme installed on the ‘images’ site. this would mean any attempt to view things on there would result in a blank page. I’m assuming this will mean that the images themselves can still be viewable across the network.

To test this idea, I’m looking for help with sourcing a ‘blank’ theme. Not a blank canvas to build a theme, just something i can load into wordpress that when activated will serve up blank pages, but still have the admin area accessable for image management.

This could just be editing the page and post templates of a wp theme to be empty and perhaps that will do the job.

Can anyone offer some advice on this that can steer me in the right direction? thanks in advance.