Well, I don't think you should be able to pick up anything from an adjacent overland map, as that would mean extending your arms 100 meters or so (I haven't even tried). As Sami said, bringing the items up there implies you were able to carry them, and so would be able to move them while carried, but that may be terribly inconvenient in the middle of winter, as you can carry unlimited amounts as long as each thing you pick up is below the limit, and so might have to shed all your clothes and other equipment to actually move with that small elk carcass.
Regardless, it doesn't seem to be a very important issue (although it might allow you to cross ice with burdens you shouldn't be able to carry across, at least not in one go).