GPS works just fine. If you have the right topo map app. I use Gaia GPS whenever I leave pavement. And I'm in my Jeep Wrangler Rubicon.
I live in this area and I use Gaia too, it’s a great app.
I’ve been mountain biking in roads in the bush around Grants Pass and there’s places I’ve been that I could swear haven’t been visited in years.
Ed