thought about a small door to slide the stock into the rack ,might do that , the main door is 6 foot wide...the coal box is in the floor dug in the the ground with a top on it and a lid , it extends out to the out side so i can reload it from the outside.
the top illustrations are of the frame, they are 2x6's on top (headder) , there is 2x4's in the middle lines , and the bottom lines are 2x4's, so there is 3 places it mount the tin, biggest span would be 4 foot in the back. 12 is 6 2 foot intervals , 16 is 8 2 foot intervals ,the top is at 2 foot centers,
here is some pics of what im talking about...