Lol, I like the maze idea, although that would be quite a bit of construction. And if it were tall enough I'm sure my BC could figure it out. She is a flexible thing! But if it were low to the ground with a "ceiling," she'd have a hard time.
And I hadn't thought of having the ADOR with a smaller plywood opening, that might do the trick. I would be installing this technically in the run (not the coop itself) but I could probably use the same idea.
I think I'll start with a 6" x 9" opening and see how the girls do, I bet they will do fine and I don't think the dog could get through that. I can always make it bigger if needed. Thanks for all the ideas!