I saw it done a few years back on a Indianna Jones. Instead of adding the lost plastic to the back, and the sides, the owner added the mirrors.

Lots of Data East games have back mirrors which look great. example Star Trek 25th Anniversary rear back mirror.

I note, that the side mirrors make a standard body look like a widebody. The widebody with the mirrors looks HUGE but bloody nice. Just add LEDS and you could stare at the machine all night. 

I reckon the Mirror look gives alot of bang for ya buck. Well done John for showing us.