I used to live outside of Prairie Grove up in that area. Nice country. The U of A up there has one of the top poultry science departments in the country thanks to Tyson's sponsorship. If you call your extension office with a chicken question they often hook you up with one of those professors. That can be a great resource.
Overkill? You can follow the link in my signature below to get my thoughts on that. I believe you should build for your comfort and convenience, the chickens will benefit from that. Because of other constraints many people build as small as they can. I understand that, we do what we can. The way you have built it should make taking care of them a pleasure, not work.