I run into a bit of the same problem with LD's. But it's even worse as an LD player won't tolerate much warping at all. And once they're warped you're kinda screwed. I've not had any problems with LD's being shipped from anywhere in the US, Japan, France, H.K., or England so far. And I'm sure you've less to worry about with Vinyl than you do with LD's.
But I think Josh gave you as good of an answer as you're going to get. Get good sturdy boxes. Pack them tight with ample padding all around if possible. And hope that whomever you have ships them at least tries to keep it orientated in the way you dictate with "this end up" stickers.