Step 1: Get a hotel in Aberdeen, Huron, Mitchell, Chamberlain, or Pierre.
Step 2: Download the GFP app or grab the GFP hunting atlas
Step 3: Hunt any of the colored squares you see until you're tired of walking
Step 4: Cruise gravel roads for the last 60-90 minutes of sunlight and road hunt. Either pick up some birds that way or use it to figure out where they are for the next day.
There is so much accessible land East River that holds pheasants that if you put on some miles you'll get some birds. If you're really struggling message me and I can be more helpful.