I was contracted to install a custom media center that included a very large TV panel. This was a two person job, but it also involved some gymnastics on my part. See photos.

Starting to make a support for the TV panel which will brace the panel as well as the eventual TV bracket.
Support installed to anchor the TV panel. Note that I used a double thickness of plywood. I’m cutting the access hole to the outlet.
The panel was so large that I had to climb on it.
Cutting an access hole on the TV panel which will mate with the hole on the support panels as well as the outlet wall. This is definitely a time to measure twice, cut once.
Job done!