I am in southern RI, so I am not as cold as you Mainers, and this will be my 3rd winter with chickens. I have a small board and batten coop that I winterize by putting up that stiff pink insulation and then wrapping the insulation with tyvek. You have to wrap it really well, especially the underside or the chickens will eat the whole thing!!!! (Really sometimes I question the intelligence of my chickens, other times I know they are brilliant!
When the temps drop below 10 degrees I run a red heat lamp out there, but I don't think they really like it. This year I have 2 BB modern game birds which I've been told need a little extra protection from the cold, so I'll run the heat lamp again (maybe below 15). I use a heated dog water bowl as well, and the deep litter method and I give them warm oatmeal with yogurt and a sprinkle of cracked corn in the mornings. . . really they aren't too spoiled. I've never had my eggs freeze I had eggs all winter, even without regular extended lights. I think there is still time for your girls to start laying. Good luck
