Sorry to keep asking questions, but I am trying to get started. I have an opening 12 inches high by 38 inches across. I was thinking 3 boxes. Now I do have a header and footer 2 inches above/below the 12 inch cut. My question is will the chickens step over a footer board and then the inches across the front to keep the hay in? In my original plan I wanted the box bottom to be below the lip so the wall would act as part of the barrier. But now that I'm looking at it, will they go inside there?