We did Yellowstone last summer and were able to reserve campsites with as little as a 1 week notice, though I would not depend on being able to get what you want with that short of notice! We reserved a space in Jackson Hole, (south of Yellowstone) with a month or so notice and were able to get a space for 5 days or so in Gardiner MT with about a week notice. If you are going to see the Black Hill is SD, be sure to watch for the Sturgis bike rally, falls around the first of August if I remember correctly, it can be hard to find a space around that time.
As far as the tripod, I don't disagree with Turbo, but we have had good luck with the tripod. I am still wanting to experiment with the landing gear stabilizers, but it is not in the budget right now
Enjoy your trip!
TV, 2000 Dodge RAM 2500 Quad cab short bed, Cummins 5.9, Edge Comp, Gauges.
5ver, 2011 Palamino Sabre 31 RETS.