If you're in the middle of Kansas and a big hailstorm comes up there isn't much you can do. There's nowhere to hide.

Kansas has trees and overpasses; it's not completely barren. I just drove through a ridiculous rain storm in Kansas two months ago and had to do exactly this.

If you're driving cross-country you're on an interstate. Park under an overpass.

And get hit from behind? No, thanks.

Interstates generally have a decent width shoulder to pull over on.

Also, it's not safe to drive during a massive hailstorm. You should be pulled over anyway.

We're talking about a car-hauler. You could run into it from behind with a loaded dump truck and do no damage (to the car-hauler).