Don't panic.
You do have a tracking number, so give that to Paypal IF there is a claim. And it is an IF, not a WHEN.
That should give you another 20 day extension on the dispute.
But, yeah, if you can't show that it is delivered, by the end of the dispute period, you will have to refund. It is a good idea for you to refund (ouch ouch ouch) rather than PP, who would give you black marks and chase you down for the money in any case.
Keep on friendly terms with your buyer. Watch the tracking. Don't worry about the lack of movement, these barcodes are only scanned when the parcel is at a new destination. Right now it probably is moving, on a container ship somewhere on the bounding deep.
Even if you do refund, keep an eye on the tracking. When you see it has arrived, invoice the customer again through Paypal. There is a very good chance that he will pay, since most people are honest, as long as you make it simple for him to do so.
And now you know why Surface is such an expensive way to ship. It's not the cost, it's the refund.