from what you say i think your coop is to small and your chickens are overcrowded. feather picking is a symptom of overcrowding. not getting outside magnifies this problem.'
half or some of the coop they have is unacessable to them as it is to dark. adding a light or window will help.
also the...
just wondering if there are any windows in the back. is it to dark? there must be a reason they are not utilizing all the space they have available.
agree that with a long winter ahead you might have an overcrowding situation in our tiny coop.