Oh Skeat....we've been down this road before with you. We've done the lightweight just barely hanging on box so that when its hit..it flies easily with only minor damage. We just hoped the kids would grow up and find something else to do. My DH became an expert at mailbox repair.
We've been really lucky since moving here...our little road has so little traffic that we haven't been hit...yet. (I've probably just jinxed us)...But, a week ago we were babysitting our friends house/animals...and yup...their mailbox was run over...the truck bumper was still laying there..the mailbox thou....it just was pushed over. Seems the guy didn't dig a very deep hole and the entire thing just pushed over and the pole didn't even break...whoda' thunk about doin' that??