That's what I did, this year and last, just cracked the single door and let them do their thing, worked really well, I used a 3inch eye hook fastened on the inside of the door for an extra inchYes I am planning on figuring out a way to do tiny doors for them. Or I may make it that the door only opens up a little bit so they can get in but the bigs can't. I may have to take out a couple of the lower bars to make the doors.
Ya I figured I would have to put something. Not sure what I want to do yet since I really don't want to deal with HWC any more than I need to. Hahaha. But not sure I want to use cardboard since I feel that kind of defeats the purpose of brooding in the coop so they can see each other.... Hmmm need to think.