Like someone said, if that rock were 3 feet in another direction, she could be DEAD. If the company doesn't think that's a serious matter, then you need to take the rock down to their place and bust out everyone of their windshields with it, smack them across the face until they are completely disfigured, then scream at them and ask them if they think it's serious, now that their lives were endangered as much as her's was. Then, tell them not only do they need to repair ALL damages, but they need to write a letter of apoligy to everyone involved and refund any lost wages or other expenses that you and your girl might have because of the matter.
Okay, I'm just venting because I got a crack in my windsheild the day after I got my car from a stupid rock being thrown from a truck. Luckly, there is a glass place near me that will repair any crack smaller than a dollar bill for free.
This isn't the case for you though... You should take this as far as you have to (and hopefully that isn't far). They are 100% obligated to cover the costs because it was pure negligence on their part to not make sure their load was secured and covered so it can't fly off.
Good luck buddy!
If all else fails, I'm sure you can rally the AT crowd to chain themselves to one of their trucks or something hippy-ish like that
