Bill in Houston from Houston on 5/2/2022 8:41:18 AM:
Maybe leave the RV in a place that it is easy to Amtrak back to. I'd probably do something like this.
Park RV in/near Sedalia.
Day one - ride to Windsor and back
Day 2 through however many - ride to St Charles. One spouse stays in the hotel or BnB with the bikes and luggage. Other Ubers to the Amtrak station and takes the train back to Sedalia.
Last day - Drive the RV from Sedalia to St Charles.
This way you can use Amtrak without having to worry about putting the bikes on the train, and you also save the quite stout expense of a shuttle.
Oh wait. 4 small dogs. If you want to ride multiple sections of the trail but be back to the RV every night for the dogs, you will need to drive to different base locations and do out and back rides, because the cost of multiple shuttles will really add up. I'd probably do base camp in Sedalia, New Franklin, Jeff City, Hermann, and Defiance.