Once upon a time, Bullhead City was called Hardyville. There used to be a toll road from Fort Whipple, just north of Prescott to Hardyville. I know at my end of the road, it's named Williamson Valley Road. Some of it is paved, but most is not. It reaches all the way to Seligman. I don't know if Seligman was along the way though.
What's left of the trail... I don't know. I'd suggest perhaps looking for the names of settlements or stage stops along the old route and searching for ghost towns.
Good luck! this could become an "expedition".