I own a dark-sky (well, dark-ish sky) California observing site in the hills northeast of Pinnacles National Monument, southeast of Hollister. It is forty fenced acres of grassland at the 3000 foot level (tops) of the Diablo Range, three miles west of Panoche Pass. This is the site called "Willow Springs 3000" at the TAC list of observing sites.
Before I bought this site I looked at, and observed from, many hilltop locations south of San Jose, in San Benito and Monterey counties and further south and I wrote up my testings of observing sites and microwave relay sites.
My site is dark for a location within two hours of San Jose. The ClearDarkSky map shows the location to be "in the blue" (Bortle 3), but it isn't really that dark. The horizons are visibly light-polluted in most directions: Hollister and Salinas to the north and west and the Central Valley towns from Merced to Fresno in the east. It is dark enough for a fine view of the Milky Way and the zodiacal light is prominent in good conditions. Normal zenith SQM readings at the site vary from 21.3 to 21.5. (It can be darker if fog and low cloud block the light pollution from Salinas.) (Note: the SQM reading at a "completely dark" site is about 21.8, not the 22.0 that you might believe from ClearDarkSky.)
The site is good for visual observing because there are no nearby light sources visible -- no porch-lights, no car lights. And the southern horizon is low and dark for reaching targets like omega Centauri and the Vela SNR.
The site is primitive with no "modern conveniences". I have two shipping containers for storage and a picnic table; there is no power or plumbing. There are minor amenities, like a generator and tools and soap and water and chairs and a car-camp potty, in one of the (normally locked) containers. The site offers little shade; I have a large tent-without-walls type shade roof that I can set up over/near the picnic table.
The last 2 1/2 miles of road is uphill dirt. In the dry, it is usually drivable by an ordinary vehicle -- one may have to carefully avoid "run off ditches" that can swallow a wheel.
The visitor should not expect cell phones to work at the site. The closest public telephone is a roadside emergency phone down on highway J-1 a bit west of the Willow Springs entrance. The CAF fire station on J-1, just east of the entrance, may be an emergency-contact alternative, I am not sure how continuously it is occupied.
The forty acres is "lot six" of the Willow Springs development, and is at the east edge of section 31 on the 7.5 minute topo Panoche Pass Calif, near the east edge of the sheet, between 4061 and 4060. You can look at the site (and see the containers) via GoogleEarth at 36 40 24.7 N 121 01 29.3 W.
Most of this GoogleEarth image is my forty acres of grasslands: the north, east, and south borders are visible because the property is fenced. (The west border is barely visible at GoogleEarth and difficult to see here; at the southwest the fencing follows the road and does not include the property's southwest corner.)
I use the flat area at the containers and the ridge above (north-northwest of) the containers for observing, the latter can be windy. There is room for about five cars-worth of observers at each spot.
The small dark non-tree NE of the containers is a "tank" or pond, formed by a dam in the gully. It is fed by runoff and by a small surface-water spring. It usually fills in the spring and retains some water all year. It would be nice to have an animal habitat there, but the main inhabitants are frogs.
After I bought the site, I observed there several nights per month, usually at new moon. I've observed there less often since 2011, because I bought another dark-sky observing site in north Arizona and often travel there at new moon. I have two telescopes at the site: a "bent" six-inch refractor RFT and a spook-modified Questar Seven on a AP-900 that is in the process of getting a pier. The bent eight-inch refractor RFT (with a flip-mirror to a four-inch) that I own is now in Arizona.
The site is fenced and unfortunately I have found it necessary to lock the gate. If you would like to observe from the site, contact me via the information at the homepage