Hmmm. We were down in that exact area for CalX 1 back in 2000. On the last day, some of us did a drive on the Old Coast Road to Bixby Bridge, coming from the south, and 4WD was not needed during any part of that. Unfortunately, I can't make out the fine details of the map you posted, plus I'm at work so I can't look at my book, but I >think< we did use that "trail" you circled. If someone hasn't already answered, I'll check on it when I get home in the morning.