It seems the high gloss protective screen on an iMac is easily removed. Underneath it the LCD screen itself is far less glossy and provides a much less reflective surface (about a 50% reduction) more suited to demanding pro’s.
The iMac high gloss protective screen is held on by magnets. Its very easy to remove, clean and replace. Just use a suction-cup (like those on brackets for attaching your sat-nav to the car windscreen, one with the suction applied by a lever is best) and latex gloves (to avoid finger marks).
Leave the screen off to maintain the low-reflection effect. And perhaps you can fabricate a replacement bevel to cover the bare metal-work and screws.
This video shows you how to remove the screen…
listen in iTunes