Full disclosure - I've never hunter pheasants in SD, but it has always piqued my interest.
Have you looked at the SD Fish & Game web site? Last time I looked - quiet a while ago - they either offered free or sold a booklet that mapped out public/walk-in lands. One thing I noted about SD pheasant hunting was that it appears that need to be really conscious of where you are at and the possible requirement for non-toxic ammo.
