I'm wanting to make the nesting box opening a little smaller since it's at coop floor level, they keep kicking the poopy shavings into the boxes, especially since the shavings are thicker for winter. The box opening height will go from 10.5" high to 8". Is that sufficient? It seems like they'd have no trouble fitting but I do have a few larger Wyandottes. I attached a pic with a board set in just to show.