Wider approximate area where she was found by jogger running in Sunnyside. It seems to be close to Highway 125. I am not sure though if that highway existed in 1978.
And more closer look at that area of Sunnyside, 2 miles east from San Miguel Road, he was jogging on Proctor Valley Road in the area where is now San Miguel Ranch. The area does not seem as desolate as further in Otey, even though Proctor Valley Road was probably still dirt road at that time.
Here is the same image of closer area but with the landscape
Link to map -
Google Maps
Edit to add: Proctor Valley Road is very long and yes it continues into national Park and desolate rural area and I think only that part has urban legend of paranormal, ghosts and spookyness attached to it for over decades. I first thought she was found dumped there but after checking the map, it was not there where she was found.
Adding few links to urban legend/ghosts stories of Proctor Valley. Check the comments too -
Proctor Valley Road Ghost Haunt Spirit - San Diego Haunted Locations
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Proctor Valley | Hidden San Diego
And quote:
Not scary enough for you? Then, how about the tale of the Haven Bakery . . . formerly in Jamul, at the other end of Proctor Valley Road, but now long gone, the bakery was run by a father with a young daughter. One day, the father comes home to the bakery from a business trip and discovers his daughter hanging by her neck from the ceiling in the basement, dead. He snaps and goes completely insane, kills all of his workers in the restaurant, stacking their bodies in the restaurant bathroom, and then hangs himself as well. Before the place was torn down in 2008, it was rumored to have been extremely haunted, particularly the bathroom and basement. The basement was rumored to contain the ghost of the little girl. Regardless it was a popular place for high school students to go at night and graffiti. Supposedly the true story is simply that a poor girl fell down the basement stairs and died later at the hospital, but a bakery massacre is much more terrifying. It might now be a Walgreens in Jamul, although no clue if it's still haunted by the ghost of the young girl.
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Proctor Valley Road - Weird California
Would be interesting to find out in which year this Bakery massacre happened.