I'll tell you from STL to Sioux Falls is a heck of a trip for your first day. Just north of the SD line is a great roadside rest, it's about an hour or so south of S.F. Gives you a chance to boondock one night. If would decide to stop there, here's secret, drive through the rest area there's road the leads to a small lake. You can park down there, it's quite and no one will bother you. If you don't like it then you can drive on. I also stop at one of the truck stops at Nebraska City. This is just in case you get tired.