I sometimes do the same thing. Stuff my helmet with gloves and other stuff, then wrap it inside my leather jacket, then jam the leather jacket in a big duffel. Then ram in others soft stuff all around. I've check this luggage that way several times, with no problems. At least everything has arrived in the same condition I sent it, and nothing visible is wrong with the helmet.

Still would be great to have one of those neoprene wetsuits like ChinaV showed us. Then pack THAT inside my jacket in my duffel....

cheers