"I do plan on using 1/2" Birch ply for the frame and top by roughly 40" high. I would also like to have a backdrop and controlled lighting on top, essentially a photo box. I have not seen any examples of a layout like that being free standing, but mounted in the wall. I understand that would be preferred, but would it be doable as a self standing layout or will that be a bit top heavy."

 I think it would be like a tall book case or china cabinet, unstable but easy to screw to a wall in a few spots for stability. Here in earthquake country we routinely attach all tall heavy items of furniture. I'd just build it with a couple of points strong enough to screw to a wall stud....DaveB

Lost of examples that are free standing, even some that are free standing against the wall so it is hard to tell.  Search Shadow box.  Here is my old free standing layout under construction.   The top hasn't been in stalled in this shot.

Your issue will be being tippy due to the narrow width.  You will have to widen the foot print at the base or have a more weight on the bottom than above and on the top

Steve

Are there other techniques to build simple benchwork for a layout like that?