Crankin', before shlepping all the way to Missouri to ride the Katy, how about the Great Allegheny Passage from Pittsburgh to Cumberland, MD? Similar unpaved rail trail, but a better surface and very nicely graded. I think you could use 28 tires on that trail. The Katy was about 90% nice firm surface, but some occasional soft patches and ruts or gravel, lots of twigs, etc. If you do hotels or B&Bs and the weather isn't too cold, you can easily get by with 2 small panniers. I carried my 2 larger panniers on this trip due to cold weather and needing more warm clothes.
Oil is good, grease is better.
2007 Peter Mooney w/S&S couplers/Terry Butterfly
1993 Bridgestone MB-3/Avocet O2 Air 40W
1980 Columbus Frame with 1970 Campy parts
1954 Raleigh 3-speed/Brooks B72