Yes, that's what it looks like. That canyon next to the red x is the Middle Fork of the King's River, near Tehipite Valley. As the crow flies, it may only be a little over 12 miles, but it would take several days of hiking to get out from there.
And, while there are lots of dirt roads in the Coast Range and the foothills of the Sierra, there is still lots of empty space there.
Then there's the empty quarter, the north east part of the state. Siskiyou county has less than 8 people per square mile.