Alaska Highway Veteran here, 5 trips up and back. Also managed a big RV park in Fairbanks for 3 summers and asked Class A owners what they had and how it went with their toads and rocks.
Most of the time, the worst damage was from people who had the solid side to side 'advertisement' the RV manufacturers put on. Big chips and marks. The next most damaged were those with the broom type. Smaller chips and marks.
After 14 years of reading, asking, and experimenting, I'd say your best protection are the two mud flaps behind the rear duals that came with the RV, and the two behind the front tires.
And it helps if you have a sloped front windshield on your toad. I only added those headlight covers from 3M to protect my toads headlights.
Other owners rave about the solid covers they mount on the front of their toads, but they're big, bulky, and expensive. I'm a full timer so really don't have a place to store them so they're not something I'd want. After 10,000 miles of towing WITHOUT anything other then the mud flaps and the 3M lens covers, I have no damage to my toad.