Yeah, I would agree that I think you've underestimated the time needed for the sort of grand adventure. Just taking adding the few extra miles to go up through the Dakotas like you've mentioned means you're looking at 6 full days behind the wheel before you even start to visit the places you've already mentioned, much less adding more things or getting off the beaten path. Certainly with 10 days, you'll have some room to explore and see some great things, but if you want to be free to enjoy the journey, then you'll need enough time to do more than just cover the miles.