When I lived in Jefferson City we fished the Missouri a lot targeting flatheads and secondary, blues. I used throw lines - 30' or so main line, 5 x 18" drops with big circle hooks. Window weight on the river end. Piece of inner tube at the top of the main line really helps. My favorite bait was live carp that we bought at Taberville. Had a great homemade bait tank. Kept stuff alive very well. We would try to go during the dark of the moon in June. Caught a lot of nice ones. Carried and used a really big net and a 4' gaff. Really big ones (30+) the gaff is the deal. Quick and very certain.
The Missouri is a very underutilized resource. Duck hunted it a lot too. Had the right boat for it 18'6" x 54 semi-vee with 50 HP Yamaha with tilt and trim.
Nice post, brought back some good memories that involve a dear friend who I lost a few years ago to cancer.
Thanks!