I was just touring these areas. Anyone on the Great Loop would have no problem because the Illinois River meets the Mississippi River just north of St Louis and just before the Missouri River joins the Mississippi. There is only one lock between the IL River and the Gulf of Mexico
(#26). It is still operating.
Also, the MS River should crest at St. Louis in the very near future. All of the bottlenecks are north of where the IL River flows into the MS.
If anyone has any questions, please let me know. I live in St. Louis during the hurricane