I live south of Springfield. I've never biked the Springfield to Kansas City route, but I've driven it several times. Terrain-rolling hills. Weather-May seems to be a bad month for storms, especially the third week of May. Main highway has a wide shoulder. I've not experienced it, but I read many bike travelogues that mention Missouri drivers are not real kind to bicycles.
Since you are riding in Missouri, did you ever consider riding the Katy Trail? Around 225 miles from Clinton, Mo to St. Charles. One of the "Rails to trails" projects. Packed limestone surface. No motorized traffic. I rode it in 2003. Had a blast.