Bob1008's L093590 worked well recently in Skagway, Alaska, where Avis is the only "name" agency. A $72 daily rate became $52, and there were no questions. In fact, the AWD number did not even appear on any of the documents printed at the location, although I of course entered the number on the on line reservation.

Interestingly, there was a sign posted that Canadian residents are not allowed by Canadian customs to drive into Canada with a US-plated rental car. Talk about a police state.