I rent surveying equipment from a place on Clairemont Mesa Blvd. Cost about $60 for a day. Takes some math skills and patience, but I find it fun. Being a professional surveyor would be cool, I think.
If the property isn’t too hilly, just try to find your corner posts by digging around or with a metal detector.
If that fails, probably smart just to hire a surveyor. Worth it in the long run to know where your property lines are for many reasons.