Maybe the old trick of knocking and listening for a hollow sound will help? 🙂
False TV wall to hide cables
Another idea would be to create a “false wall” to mount your TV and secure it midway in the PAX. The PAX is quite deep for a flat screen TV, even if you’re using the shallower frame.
Make the panel out of MDF or plywood and hide your cables behind the panel. Then you’ll only make a small hole in the PAX top panel for your main power cable to go though and reduce your risk of hitting the solid panel and filler.
Or better yet, relocate your power point to behind the false wall.
Any one with better advice?
And when you do cut the frame, come back here and share your knowledge. We need this information!