There's a section just for trikes on CGoaB, and I'm sure some of them discuss shipment in their journals. Even if they don't, you may be able to post a message there, too. Here's the link to the list:
http://www.crazyguyonabike.com/journ...category_id=22
Heidi D. has a picture of the box she built to ship her trike here:
http://www.crazyguyonabike.com/journ..._id=21771&v=3x