I remember that day. That was my first Kansas tornado, up there near Hill City. I had much the same view as you. Watched the initial mesocyclone develop and tease for a while with a few funnels that never quite got going, then occlude as a new meso formed and strengthened south of it. That one did the trick. The storm had some really beautiful structure.
Wonderful structure day indeed! I have attached a pic the mothership taken about 12 miles or so south of Hill City. This was a classic mesocyclone that produced some of the best structure I had seen to that point.