Has anyone tried installing heavy overlapping vinyl/plastic strips in the coop's door opening? I've seen these used to keep the cold out (or in) big commercial freezers, or in bay doors for loading docks. You just push through the plastic strips to get in or out. Would chickens have problems learning to get in or out of their coop through the strips? This would be in addition to the normal wood latching door for the coop. I was thinking about helping keep the heat in the coop during the winter, but make it easy for the girls to enter and exit once the wooden door had been opened.