I don’t think I’m quite talented enough for to create what you want, but if you want to use the background, I’m sure I made overlays and shared them in my drive – so you’d be able to use the mirror in the original background. 
edit, adding link to my drive, everything is in folders by Catalog Name to make it easy to spot what you need.:Episode Overlays, Free Use Oh, and if you see one I missed, just comment on the thread and I’ll get them done as soon as I can
Hope this helps you-- I have done quite a few of the backgrounds from the portal that weren’t usable because furniture, etc. were in the way, so maybe it’ll be helpful in future.