I've got one of my setups in the same scenario as you do. When the corn is still up, I set up in the hay field. If the farmer has chopped the corn (stocks cut low) I usually setup in the corn. If the corn was picked and the stocks are long I setup in the hay field with some of the dekes in the corn. I normally don't see geese landing in the taller stocks. Usually they will land short and walk in. You can also try driving or stomping down an area in the corn and spread the dekes there, giving them a place to land.