According to the manual you need 12" between the rear corner and the wall for clearance even with a protected surface. Maybe the picture is misleading but are you sure you have that?
Interesting idea. Was that in there when you moved in or did you add those openings?
It was there when we bought it a year ago.
Checked the clearance. I have 11" to the knotty pine wall with a row of brick in front of the wall. Stove is pretty hot and bricks are only warm.