Well, Pat, that's coming along beautifully. I suppose the main details would be stacks and stacks of lumber and something to move the lumber with. I plan on using a couple of these to move lumber:
http://www.walthers.com/exec/productinfo/786-5109 in addition to a tram system.
Then there's the matter of a kiln; every planing mill had a drying kiln. They produced kiln-dried as well as air-dried lumber. The lumber was generally rolled into the kiln on some sort of metal carts and remained on the cart during the drying process as I understand it. The work are was kept generally clear of junk to prevent accidents, but I'm sure there would be a pile of banged-ip boards around, maybe with some wire banding in it too. I'd put one near the kiln and another near wherever I load the lumber onto the railroad cars. And, I'd work dirt and ground cover right into the pile, as if the pile had been growing over time.
But, what you've got there so far is terrific!
--Stu--