Photoshop Guide Only Layer (Non-printing; does not export)

I am currently working on a template for headshots with the upcoming election and want to show a 'live area' for clients to reference when aligning their photos to the guide. A cropped artboard would not work in this case, since the program we upload the final to will crop the image according to the info submitted.

My idea is to have the ability to turn a layer, into a 'guide only' layer. Like the one in After Effects, a layer that you can leave the visibility on and it won't export with the final.

A lot of what we do as designers is to make the hand-off as easy to use as possible. This would be a useful feature for templates.