I did the pretty much the same thing using "this map". I too found that there were siginificant differences between that map and what my Benchmark maps showed especially where it crossed 89 alt east of Prescott.
I didn't know about the picture map overlay feature in Google Earth. I will try it out.
BTW has anybody had any trouble riding Crawdaddys route along the eastern rim of the Grand Canyon? I think the fact that is on Navajo land is reason it is not in the GWT.
We rode some dirt roads on the res in wester NM and eastern AZ on our trip last week, and nobody bothered us. But they were marked as county roads on all my maps.