Try Harry S. Truman Reservior. My parents live on the banks of the Grand River between Clinton and Warsaw, Mo.
Ther isn't a weekend goes by in the Spring, Summer, and Fall, that Bass boats don't go roaring past their place. from Bass tourneys.
For contacts and info., try Bucksaw Point Marina, Long Shoal Marina, and Harry S. Truman State Park/Marina. Maybe even the Warsaw, Mo. Chamber of Commerce. Many Bass tourneys launch from the above marinas.
Sometimes there are 1-5 going on at once on the weekends.