As you know, we've done similar to what you're proposing twice in the last 3 years. The first trip, we had zero thoughts of driving too much. This second trip was a little different. I think the "newness" of adventure had worn off a bit. We averaged 500 a day for 3 days. We did it...it wasn't miserable...but it wasn't fun. I'll always vote for push yourself if that's the only option you have.
A few comments I saw that I would second. First, 10 days at Yellowstone is not necessary. I would suggest 3 days for the Tetons and 5 max for Yellowstone. In 5 days, you can see all there is to see from the roads. I didn't realize, but many or most of the road stops include 1 mile or so boardwalk hikes. That was enough for us on the first visit. Second, use the Black hills as a 3-4 day break on the way out, and Badlands as a 2 day break on the way home. Or reverse that. That way, the long stretch has a rest in it. BTW, we enjoyed the SD attractions more than Yellowstone.
