Good question...that I don't have the answer to. But I am mixing geese and field ducks as well. No dog, no boat, so I can walk to kills.
As I understand the geese will NOT fly over ducks to land, also I believe the geese want to be farther from ANY cover, trees, high weeds that may cover predators.
Hope this helps a bit? At least til someone truly knowledgable chimes in.