Removed the old TV. Put 2X4 spacers around inside of opening frame. Mounted a piece of plywood on 2X4 to mount TV arm on. This allowed TV yo swing out and give access to area where original TV was mounted. Lots of storage.
Here is a picture. Large holes are for access to top bolts. Bottom board was at top of opening for original TV. It has magnetic latches.
Picture of TV in place.
I added insulation behind entertainment cabinets. While it may have helped. It hard to tell because cab area seems to have more heat or cold.