I saw this while planning out a future trip involving the new Ste Genevieve National Historical Park in Ste Genevieve, MO. There is a ferry over the Mississippi to Modoc, IL. I was looking at taking it eastbound on our way back, but now I think we're hitting in heading westbound. But, depending on what time we finish at the park, there may still be time to take the ferry and make a big circle back over the Mississippi and continue on our way.
MO 32 ends in Ste Genevieve and then it is just a plain road down to the ferry and a plain road on the IL side into Modoc. Once in Modoc, if you turn left you get to IL 155 which has a waypoint for CR7. If you head straight, it eventually meets up with IL 3 and IL 155 where there is a waypoint. It is the turning right that I am talking about. It becomes Bluff Road and then Roots Road and reaches IL 3 near Ellis Grove. There is no waypoint there, so that's where I am suggesting one. This would split the 8.80 mile segment between LibSt and ShaTr roughly in half. I did that intersection on Google Maps and came up with 38.017249, -89.907892.
Mike