As a ex NZ Ground Supervisor, I really wouldn't recommend it. Doesnt matter how many fragile stickers are on it, it WILL get banged around a bit. I have seen many a duty free or wine bottles smashed.
You are correct in that the two boxes tapped together will count as one item. As long as it weighs under 23kg.
You are better off taking it as carry on if you can, or Fast Bagging it. Good luck
