fischer, way to go with your close eye on the flock. Good flock management is always making sure the ones in your care, are being taken care of in a win, win, situation for you and the birds.
I'm thinking that your insulated coop with less than really extreme temps would work fine with the light being set on a timer.
I use one when i choose to extend the light hours to the optimim 14 hours for laying.(sometimes it's good to give the flock a needed rest)
I chose to raise a backyard flock to benefit the birds, creating the environment God ment for them. I would never alter my birds for any reason....that's my choice, and yours too!
bigzio