Area behind the 3rd seat. I used 14x 24 for the measurement. Note chair all the way back toward wall.
Found these at Home Depot, $6.98 each measurements were perfect.
Moved chair all the way up, swiveled around to work in the area.
Shelves installed, put some junk in them so you can see better with the white background. Shelves came with hardware to attach. I used level to make sure shelves were aligned. I took a razor blade and cut some 6inch strip of duct tape to put on back of the vertical rails to hopefully help with the ole rattles, two strips each. May use some plastic bins to put inside of shelves. Also do not plan on putting a lot of weight in them.
Shelves with 3rd seat back in position... Shelves do not bother head unless you lean pretty far back.
NOTES: Project time about an hour. Used level for alignment. Used scribe to mark screw holes, I HAND SCREWED them, did not want to over tighten with drill.