Here is what I could get.
Unfortunately I have deleted the original photos of before I started. Like I said the spacing between the TV and trim was tight but accessible. The top trim is removable by 3 screws from the back of the trim. The first photo are 2 of the screws at the bottom, then next photo are the top screws. There are 4 screws on the bottom and top. The last photo is the self I made from wood I bought at Lowes, it was medium density board with a cherry laminated finish.
If you what to know how I mounted the larger TV as well as making the self just let me know.