Two large panniers and a rack pack will do it, especially if no kitchen, or even if there is. I know as I did a week tour one time and forgot to bring the front rack. Didn't realize it until I got to the start point, 400 miles away.
A circle tour is nearly always better than an out and back. Psychologically and for scenery. If you could manage the time, try and include a ride down the Mickelson trail from Deadwood to Crazy Horse Monument and even Mt. Rushmore. Check the bicycle options on Google maps.
Either way, you're gonna have to push it to do this in 2 weeks and have much time for sight seeing and/or headwinds.