If needed, here an interesting link about French light houses during the war (in french):
http://www.cairn.info/revue-guerres-...4-page-109.htm
To resume, light houses activity was normal untill German invasion in France. Then they controlled all light houses activity by a progressive black out (mainly to avoid ennemy plane bombing), only lightning those light houses when they needed it, for krieksmarine and merchant convoys leaving/entering zone.
That makes me think would be nice to have no working light houses ingame, but after a radio asking they should work for our need!