Looks like you are new here.
Not sure what you are looking for in terms of riding and accommodations.
I have ridden this section a couple of time in the past 25 years.
There is an absolutely delightful stretch from Mount Carmel to Centralia in Illinois.
Paved county roads with very light traffic - much better than US 50.
From Centralia there are a couple of options with only moderate traffic.
I would urge you to cross the Mississippi on the historic Eads Bridge.
The first bridge at St. Louis, the Eads has been recently restored -
Arches are underneath, so you have a 180-degree panorama of the city and the Arch.
As for Indiana, it's a little tougher.
Southern Indiana is a region called "The Knobs" - dozens of north-south limestone ridges.
Which ain't exactly wonderful for cyclists going east or west.
I have followed the Ohio River west of Cincinnati - thru Rising Sun to Madison.
Then there you can take fairly minor state and county roads west.
Be glad to share more details if you wish.