site: Pinnacles East
Pinnacles National Park - East side
Visitors, including astronomers, must pay day use fees (unless you have a national park pass).
East Side has steep ridges on both sides of entrance, there is, however, a campground (privately operated park concession), which requires reservations. Campground itself is rather sandy, but there are a few places to setup telescopes in the parking lots farther up, specifically the Bear Gulch parking lot and trailhead.
Directions: Take 101 - 152 to Hollister, go south on 25 umpteen miles, turn into the park on 146
https://www.nps.gov/pinn/planyourvisit/maps.htm is a handy map for the whole park.