Tom,
You're right, I'm not going to want to answer your question in a post, there's too much to say. Both Gil and I commented on how the three of us came up with certain aspects of the routing in some earlier posts, and perhaps it would make for an interesting article, I don't know.
I will say that most of the holes were placed because of their natural features. We knew #13 would have pretty framing
and some interesting rolls, significant width and the boundary road along the right, but it did not have any single feature jump out. Which is why there was so much uncertainty as to what we should do with it, and thus, why I put the disclaimer at the beginning of the article that #13 involved a unique and different approach prior to construction.
Geoff