Waggles, I suggest that you tow a 6x4 trailer. And if you really want to be nice to inattentive cyclists, keep an old mattress in it.
I ride to work most days. I have a little sympathy for other cyclists but for Pete's sake it's up to them to KEEP ALERT. I wonder whether the guy who launched into your rear window was listenting to his iPod at the time. I see that all the time, and in peak hour commuter traffic. It's just nuts.
One of the guys in our neighbourhood recently rode into the back of a tray truck that was parked on the side of the road near the bottom of a hill. 2 broken legs, broken arm, broken ribs and pelvis, broken jaw. As a doctor, he was probably not in a good way to diagnose all his injuries.
I don't think there's anything you can do, although parking on a climb rather than a descent might mitigate the damage. Or if it's flat, only park there when there's a 30kt headwind!