Oh I so don't have time to work on this right now. But, since I went through the trouble to make a detailed graph (not that much work, actually), I figured I'd share it.
It's too big to post here, I think, so a link instead: here
It's a large graph, and it needs to be resized a bit to fit on 8.5x11 paper. In order to get the level of detail I wanted, I needed to make an extremely large graph. It crosses 108 stitches and 217 rows at a ratio of 20s x 27r for a 4" square.
Actually, when/if I make this, I may scale it even larger for even more fine detail. As it is, this would only really fit on a blanket or a coat unless one was working in thread, and even then it would not be small.
Lastly, I think I'd still do this in duplicate stitch. Intarsia would be a pain, and the color changes are just not frequent enough for fair isle work.