Have you looked through the coops in the resource and article pages yet?
Good point. I've collected some links for well-designed smaller coops here:
https://www.backyardchickens.com/articles/dallas-urban-coop-single-slope-design.72422/
https://www.backyardchickens.com/articles/yakisugi-coop.76398/
https://www.backyardchickens.com/articles/coreys-coop-de-doop.55619/