I'm going to leave Walking Box Ranch Road here and follow this smaller road at my left toward Castle Peaks
A few minutes ago, I passed a car, which turned out to be from the "4WD group" I saw earlier (biologists, actually). It was enjoyable talking to the driver, who has knowledge of this area.
He pointed out that the old power lines on Walking Box Ranch Road had been recently removed. I hadn't noticed, but as soon as he mentioned it, I remembered those power lines from previous trips here.