Southeastern Wisconsin to Mt. Rushmore- need advice:)

We are looking into traveling to Hill City, SD. Want to stay at Rafter J. We will be taking our TT. Just looking for places to stop, places to plug in for the night and must see's. Last year we traveled from Waukesha, Wi to MA. We were able to stop on the turnpike in Ohio (there and back) and plug in for the night. We loved it! We would love to do that again if possible. What are our options?