Love the hardware cloth idea.
This is the one I'm getting: http://smile.amazon.com/gp/product/B003JP4928/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 It has a removable bottom (velcro) that I'll remove and then put it on the floor of the coop. I'll put a few inches of clean shavings inside it along with the nest box. Then when they get big enough, they can go in or out as they wish. I hope this works.