I don't have a tractor with a bucket (darn it) or a need to plow snow, but I'm wondering if some sort of hooks on top of the plow with round stock (I'm thinking 2 inch thick walled pipe) welded to the top edge of the bucket might work. Leave the plow leaning up against a wall or post, tilt the bucket opening towards the ground, drive up to the plow, come under the hooks and rotate the bucket so the opening is horizontal. The weight would hold the bucket on. Reverse to drop the plow when you need the bucket.