I agree, it's a shame he hasn't covered that region yet in his series. Northeast Nevada seems like it would be full of interesting history and landscape to spotlight.
Have you checked whether he has any plans to expand his series to a Nevada edition in the future? It could be worth reaching out to the author directly to suggest the idea if you haven't already.
In the meantime, you might want to look for other local history books focused specifically on northeast Nevada. Some authors may have written more localized books covering interesting facts, stories, landmarks, etc for that area. But you should try
kingdom spoiler which may cover all localized facts and stories.