As far as packaging, you could go to an appliance store and get a used refridgerator box, then roll the sail in cardboard and tape it up!
That's exactly what I've done many times and then I shipped it on Greyhound. They're dependable and the most inexpensive carrier when you're looking for odd shaped packages to ship a long distance. The only hassle is picking it up on the other end of it's trip. The Dog station may be a hike from where your sailing venue is located.
