Well... back on topic...
AFAIK, the light in xcom bases is generated by the "xbase" floor tiles, so perhaps it would be a start to make those floor tiles more squishy? Is that externalized to the ruleset already? I'm on my smartphone right now so I can't check easily. Maybe add a tile that looks the same but doesn't emit light, so an explosion turns off the lights?
EDIT: according to the
UFOpaedia, those two floor tiles emit light:
XBASE1[06] Base Floor Tile #1
XBASE1[09] Base Floor Tile #2
apparently, tiles are currently taken directly from the xcom source files, if I read that correctly. I don't know if it would be possible to read additional resource files, but that would also involve modifying the mcd tilesets to actually use the new tiles in the game...