Well, I settled on this route: http://www.mapmyride.com/route/us/ia/keokuk/263958621

It's basically the route above with a couple shortcuts added to cut out 2 miles of pain.

Tomorrow's the day. The weather is looking good so far, but I just cleaned my bike, so it is bound to rain (which will feel good if it hits 90 degrees). I'm hoping to finish under 13 hours. Stay tuned for a ride report.