If you haven't already, check blogs on Crazy Guy on a Bike. Lots of cross-country tours documenting many paths across the US. One that I am currently reading that is an "adjusted" Trans-Am tour is "Portland to Portland". They left Portland OR headed for Portland ME, and adjusted mid-tour to include the Katy. They are in New York state right now. Bottom line, you can't go wrong adjusting a Trans Am tour to include the Katy Trail (and, now, Rock Island spur).