So the revisions I played around with this past week, and printed out 1:1 on copy paper, and then taped together come out to around 12 feet. I had to compromise the yards design a little, but it's still pretty faithful to the prototype drawing I have, except for the fact that I added an extra ladder track and a couple of turnouts.
Compare my final revision:
To the scan I posted a couple weeks ago:
I'd say they're pretty damn close, and I'm happy with the result.
This is what it will look built:
Thirteen sheets at 8 1/2" x 11" is a pretty decent size. As always, comments are welcome.