Welcome aboard the RoadTrip America Forums!

On 'day' 18 you are planning on driving 650 miles overnight? That is near-suicidal. On day 10 you are planning on driving 850 miles overnight? That is even worse. I presume that the fact that you have these two drives highlighted in your spreadsheet means that you are aware that there "might be a problem", but it goes beyond than that. Even if you survive both drives, the next day in each case will be a total waste as you WILL be tired and out of sorts. And yet on the day following your second overnight drive you plan to see the Badlands, Devils Tower and Mount Rushmore AND drive another 375 miles! At least on day 11 your schedule acknowledges the futility of doing anything in one of the most beautiful places on Earth but "rest". I'm sorry, but these two instances of over-optimistic planning will have to go if you really want a safe and enjoyable trip.

AZBuck