I decided to keep it simple for the wall mount. So, I cut some plywood up, drill a hole to accept a drywall screw, and then glued the boards to the back of the glass. Here they are setting up:
Here is the diptych mounted on the wall, in studio (florescent) light:
And under tungsten light:
Now I mail these suckers off and have only my backer eldest bro and nephew to deal with. They want "something special", and I have no idea what that would be. I think my nephew is submitting a drawing that I have to render.