A bit surprising the path would be in that bad of a shape--that was a limestone-paved part? C&O is clay-dirt/gravel/small rocks but sections near DC seem as if they'd be fairly comfortable with ~50 mm tires.

If they have a big trail ride during or after periods of much rainfall it can destroy the trail (I live near the Katy Trail).

Of more importance is this:

ADVOCACY ALERT: Bill to allow ATVs on the Katy Trail moving forward in the Missouri House; contact your representative today | Missouri Bicycle and Pedestrian Federation

+1, we rode the katy one year after some significant rain just east of Clinton, and the trail was in terrible condition after some herd of horses had been thru.

I loved the Katy Trail. But I always mix hotels with camping on account of I hate camping unless the weather is good and the camping area is attractive. This being said, I only camped once the whole time. I think it would be pretty easy to bivouac along the trail in many locations. Watch for poison ivy, ticks, chiggers, etc.

We enjoyed the Katy Trail a few summers ago, rode from Clinton to St. Charles in three and a half days. After being shuttled to Clinton and spending the night there in a motel, we rode from Clinton to Pilot Grove the first day of riding, camped in the city park in Pilot Grove, about 62 miles for the day. The second day we rode from Pilot Grove to North Jefferson, about 62-63 miles I believe, then took the Truman Hotel shuttle into Jefferson City (bikes and gear loaded neatly in the shuttle van, a nice surprise) and had a nice stay at the hotel, enjoyed the restaurants, getting cleaned up, etc (this was August, it was hot and dusty on the trail). The third day, after getting shuttled by the hotel back to the North Jefferson trailhead, we rode from North Jefferson to Marthasville, about 65 miles for the day, I believe. We camped in the baseball field complex, were given access to the bathrooms and showers at the ball park; we camped between the ball fields. The fourth day we only had 40-45 miles of riding back to St. Charles, we finished the ride in the early afternoon. A great trip.

The best time is in the fall.
The water level on the Missouri River is low.
The water table is low. Therefore less ruts, mud, bugs....etc.
the bike tourists are low in number also.
Camping is much easier. Stealth right on the trail.

Anything in particular to say about groceries? I did look at the map and they seem to be often enough.

Simply take a couple spare meals with you and get your groceries when you can, because you just don't know what will be open when you happen to pass thru. Last October, they were not always that plentiful at times, unless you were willing to leave the trail a significant distance.

Yep. Small, country places don't always keep "big city" hours. Edgemont, SD is at the southern end of the Mickelson Trail. There is a small market that closes at 5 p.m. It's not open at all on Sundays. I hit town after 5 p.m. on a Saturday and had to eat out. A few years ago, while touring in MT, I stopped for groceries 18 miles before my campground because I was worried about the selection at, and the hours of, the country store connected with the campground. I arrived at maybe 5:02 and the store was dark and locked up tight. There was a couple behind me that was supposed to stay at the same place. Worried about them, I actually saved some of my provisions for them in case they showed up worth nothing to eat. Turned out they got a room at a place with a restaurant because of the off and on rain showers and hail.

I don't care what everyone else says, you really are a nice person.

A few days later I ended up staying with them at the Bike Camp in Twin Bridges, MT. I gave them some leaf spinach I couldn't use to add to their dinner.

About the closest "good" campgrounds to STL are Klondike and Marthasville.
Have you heard anymore about the new stretch they're building?
I've never done it, but I think stealth camping would be quite easy.
I regularly ride Black Walnut to St. Charles, get in a couple of loops on Bangert Island, grab a snack or lunch, then ride back to Black Walnut.

I just trow up my tent up wherever I happen to be around sunset. If I'm more than a few miles before a town. Most towns have actual camp sites also.

The new stretch is the Rock Island trail from Pleasant Hill, MO to Windsor (connection with the Katy). It will be open by the end of this year. Camping will be permitted in the city parks in Pleasant Hill, Chilhowee, Leeton and Windsor.

Im doing a 3 day 2 night ride on the Katy trail in 5 weeks. Should be a blast.
The trail is about as well set up for an easy trip as you can hope for. There are hotels and b&bs all along the trail, and camping spots are all along the trail too.

Ride east from Sedalia, camp a couple nights, and then hop on the train once finished to get back to Sedalia.

Just make sure you get your train tickets early enough that you can get a pass for your bike as well. They only allow 4 bikes on the train at a time and those spots fill quickly. Also, if you're counting on bed and breakfasts for lodging, make sure you call ahead because even though the BikeKaty website shows it's open for business, it may not still be open.

Thanks for the advice.

We snagged tickets a few days ago to ensure the bikes wouldnt be an issue, and are camping on the ride.
Im sure ill be heading back next year with family and will go the B&B route, so there will be lots of calling ahead to make sure places are open and available.

Smart man. One of the friends I went with last October didn't believe me and waited until the last moment to snag his ticket. Found there was no room for his bike and the train conductor wouldn't budge. This threw a wrench in his plans and he spent the evening camping out unexpectedly along the trail near Sedalia.