Damn, that's way too cold homes! IDK if your girl is setup directly in your back yard or not. If so, I'd recommend using a couple posts & some 4 mill clear plastic purchased from home depot/lowes and create a lil cover for your girls that will still allow sunlight thru. This cover will help keep them warm, and then another way you could take it further would be to throw a small electric space heater on an extension cord and put it next to the plant at night while it's covered so it stays warm. Only thing about the heater is small ones with temperature pre-sets are ideal so that it doesn't get TOO hot and not turn off, as well as duct tape any led lights or anything on it that could in any way interupt the light cycle at night. If you do all this and allow your plants another two weeks, this time & effort should pay for itself in yield. I lived in the Rockies for a while tho, so I know how stuburn that early winter weather can be. Sounds like you will be seeing some snowfall soon?
Hope you can give her a bit longer, but if not, post some pics of the final product and lets see what you're working with! =)