We are in the design phase of our coop and I'm trying to nail down some dimensions. The coop will be on a concrete slab and the adjacent run will be on our (very sandy) dirt. With that in mind I'd like to utilize the area under the coop for additional run space. What head height would be optimal for dimension "A" in the diagram? We will be using a 24" deep poop board under our roost. I would like the area under the poop board to be as flexible as possible so that we can use that space for different options - feeding/watering area, nest boxes, or brooder box. With that in mind what head height would be optimal for dimension "B" in the diagram? The dimension "C" shows the height of the poop board and where the clean-out door will be (for the poop board, there will be another clean-out door for the entire coop). I'd like to keep that dimension under 42", if at all possible. I'm also estimating 11" for the various structural pieces. So A + B + 11" = < 42". Keep in mind that the dimensions A and B are the head height under the "rafters" and that there will be an additional 3 1/2" in between.