For those who might want to go the private route in the future!…
I would suggest you to go to the post office and order as many registered mail “BARCODE LABELS” as you can get. They will be very beneficial in your journey! If they as why you need them, tell them you do a lot of international shipping and need them for your orders and tracking purposes.
This is not legal advice but of any kind. Just a friendly piece of educational advice.