[davidw]

The one for Oregon looks suspect as well.

If I had to make a gut call, I'd say somewhere between Lake Abert and Steens Mountain, or perhaps somewhere in the extreme southeast portion of the state. Those places all have "roads" though, I suppose. Not paved ones, but someone drove a truck back and forth in the sagebrush a few times, and it wound up on a map. Still, they are extremely remote.

Edit: interestingly enough, the McFurthest spot, linked in my other comment, is between Lake Abert and Steens mountain, albeit to the south, in Nevada.