Is there any way to make the keycaps out of UV reactive plastic? Then if UV LEDs were used for the backlighting, the keycaps would react to UV light and glow. This would pretty much eliminate the light between the key caps, as you simply would not be able to see it.

Using my blacklight, I see that on my 82 key that the spacebar does seem to react to the UV, but the other keys don't.
I'm going to guess that the needed UV LEDs would be a bit spendy though...