can't remember if there's a sign at the intersection, but I think it's the only paved road heading south in this vicinity. Nothing to confuse it with. It is indeed a long and hilly way around to avoid a couple miles of gravel...but i guess if you've got serious skinnys for tyres, that gravel may seem like an eternity...but in my experience, on 28c it's just fine.
This map may help a bit, especially with avoiding the Panther Creek Rd., which is shown misleadingly as the main thoroughfare on many maps.
see Route 3, map 2 ---
Also -- There's a reason it's not paved all the way through. The BLM, who owns the gravel section, wanted to pave it back about 10 years ago, but the folks who live along the road were adamently opposed - they were legitimately concerned about it becoming a more of the thoroughfare between the valley and the coast (more traffic). So the BLM responded by saying the road wasn't safe in current condition (which is kind of strange because they've got plenty of roads far worse, it would seem..?) , and closed a portion of the middle section. It was like this for several years, and to my mind they could of left it that way forever - great for bicycling. Finally they came to some sort of an agreement not to pave it, and that it was reasonably safe, & the barricades came down.