Sounds like a nice break, wish I lived close enough to the Katy to do that. I usualy just bring a super minimal kit and a fixed gear for that trail. Its a nice flat ride.
Water is a suprising problem, I generaly bring several bladders and bottles or some 2 liter soda jugs with h2o, depending on my rig and plan. I live a few hours from Clinton.

I also once helped a guy on the trail, a nice old treck that had seen no maintainance for twenty years, had a broken chain. The rider and his wife were outside one of the biker type bars on the trail, with no phone reception. they said the watched me coming for a mile or so, with thier fingers crossed because I had a full load and looked like I might be prepared. That is the only time I have used a chain tool on tour, and i hope its my last.

Stealth camping is not really encouraged on the Katy, no. However, I have done it once, when I hit the trail around matchens coming south as part of a longer tour. It was to late to find any campground, and there was a nice patch of woods...
Early that morning I figured why they did not want lots of people camping at random, when I really had to use a toilet. Five am, on the trail, nothing in sight
Lucky as an experienced tourer/backpacker, I used a bag that I generaly keep for the purpose(Some trails require that you pack EVERYTHING out). A few minutes later I came on a trailhead where I was able to dispose of things. But can you imagine if lots of people started using the bushes on the trail? It would get pretty nasty. As it is, I have encountered several deposits right smack dab in the middle of the trail