PCT Southern CA section

Nicole,  The section of the PCT as it runs thru the Tehachapi’s isn’t easily accessible. As you have probably already figured out, the only “easy places to get off trail would be Hwy 58 between Mojave & Tehachapi, Hwy 178 at Walker Pass and at Kennedy Meadows.   You could use Kelso Vally Road but I wouldn’t say that to be a “best place” to get off the trail.  My first choice would be to either hike to Kennedy Meadows or, if possible, hike to Cottonwood Pass and exit out of Horseshoe Meadow, SW of Lone Pine.

Walker pass use to have bus service.  You should check if it still runs.

https://www.pcta.org/2014/public-transit-pct-walker-pass-lake-isabella-ridgecrest-23785/

That said, every year, plenty of hikers have hitched out of Kennedy Meadows to town to catch a bus either out of Lone Pine or Ridgecrest.  Here are the regional bus routes of the area you are interested in: http://kerntransit.org/routes-and-schedules/