Canada uses the chip seal method which leaves a lot of debris on the road and this was consistent on significant portions of the Alaskan highway. About all you can do is slow down and pull over to the right as far as possible. Most trucks pull over to the right, RV tourists are largely clueless and the locals generally don't care because they live in that environment.
The best toad protection is a Protect A Tow type device. If you have a rear mudflap and it's lower that 5" remove it so that it cannot kick up rocks. Vertical shields can reflect rocks forward and would not protect all of my radiator. The bra device works but will need to be washed after every drive or the accumulated dirt will wear on the paint.