Don't freeze wine that hasn't been opened. It could expand and cause the cork to pop slightly, ruining the seal.
Someone like Pyang might have some options because people send their collections for auction all the time. How do they do it in the summer?
Also, you might personally transport all of your wine across the border, then store it somewhere near the border in the US until it can be safely shipped to you. I would think that it would be easier to have it professionally transported inside the US rather than across the border.