Propane tank cover modification

New style dual tank regulators have a status view window on the front as opposed to the top. This makes it difficult to check the status of the tanks if a switch over has occurred without pulling the plastic cover off. Of course, you can cut a hole in the front of the plastic cover and install a plexiglass piece to serve as a window, but I am wondering whether there is a nifty commercial item that would do the job. I've seen a commercial portal used, but I have no idea where it came from and searches have turned up nuttin. Any ideas.