Im no expert, but in Feb, people are already killing a lot of snows in mound city, missouri. Given that missouri is a state distance away and if weather is turning out nice. Hit SD on March 15. Just realize SD has different rules and off the top of my head, I think there is still a 20/day limit. And I dont even know if the application to hunt waterfowl in that state carries over to conservation. Limited out of state licenses for waterfowling. Check before you. If I was you, I go to the Mecca of Mound City.
DUCK HUNTING ITS NOT ABOUT THE BAG ITS ABOUT GETTING AWAY