I am no expert and don't have any data to support this but....it seems that once the snow gets too deep (1"+) and or when it gets a crust on top they just don't dig for forage too much. they do more browsing then. if that is indeed the case (not saying it is 100% true) then nothing you plant for winter feed will work in your climate. Standing corn could be an option but sounds like the pH will limit you there. Don't know if it's legal, but corn products are sure to provide deer (& turkeys, squirrels, etc) with feed. NY has restrictions on feeding deer (concerns with CWD), however a little cracked corn never hurts []. Maybe berry producing shrubs that tolerate your conditions might be a way to go??