I absolutely agree that driving slower will help and perhaps that's why I didn't have any significant damage to the front of the motorhome.
While I respect Joes comments and many years of experience our single 2013 trip led us to conclude:
1. The fastest drivers were the locals when towing or not.
2. Many/most of the cars/trucks in Whitehorse have broken windshields and apparently they will not be repaired.
3. We wondered if the locals simply accepted rock damage as a condition of living there just like the weather that they can't control.
4. The most considerate drivers were indeed the big trucks (I posted big rig above). This group consistently moved to far right as possible.
5. Very few locals moved to the right.
6. Very few visitors moved to the right.
There were very few rocks on the paved Alaskan roads.
If you drive to Alaska you should expect that rock damage may occur and it's more likely than in the states. But if you don't go then you'll miss out on a great trip and adventure.