Ft. Scott is on the eastern side of Kansas and you can walk all around the old fort which has been well maintained.
Traveling west you can spend the night at Elk City State Park. If you are into hiking they have some great trails. One is 15 miles long and people often backpack and spend the night beside the trail. All of the trails wander through trees and rocky bluffs.
The only thing I know of interest in Dodge City is Boot Hill. You could probably spend a couple of hours there. In the early seventies I spent some time in Dodge City and at that time there were only two campgrounds. Now there is a meat packing plant and I am guessing that lots of the workers are living in trailers in those campgrounds. I think one of the best campgrounds is on the west side and they close and lock the gates at 10pm. This is what they did a few years back, don't know about today.