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".
Paved roads are just for getting you to the starting point!