In 40 minutes driving north from Mountain View I think you'll be in SF at best.
You might make it to North Bay/Marin - which is true that it's rural, but it's not because it's a secret or far from humanity or anything. It just has the fiercest NIMBYs on the planet who are fine with all their services being provided by day laborers with 2 hour commutes.
Are we talking about SF or mountain view? 40 minutes north of SF is beyond Marin. Remember that this is about living comfortably on $5,000 per month for rent. That should get a pretty incredible place anywhere north of the golden gate bridge.
You might make it to North Bay/Marin - which is true that it's rural, but it's not because it's a secret or far from humanity or anything. It just has the fiercest NIMBYs on the planet who are fine with all their services being provided by day laborers with 2 hour commutes.