I drove the Ridgecrest Drive up towards the summits of Mount Tamalpais and drove past the gated road that led to the West Peak--the signs on the gate looked pretty intimidating. Instead, I drove on up to a height-of-land on the road a bit further uphill, at WGS84 37.92276, -122.59659. There was parking on the right shoulder for a couple of cars.
Across the road from this spot was a path leading uphill. It started out pretty wide but soon became brushy and overgrown. A fence that used to be there was completely gone as the path slabbed up the hill, remnants of it were visible on either side. The trail pretty much completely disappeared as it neared the summit area, but a very short bushwhack brought me to the main fence around the summit compound, on its south side. This fence was festooned with many threatening signs and it definitely seemed like a bad idea to try to climb over it.
I turned right (east) to start circumnavigating the fenceline. A short 5-foot uphill section brought me up to the level of the large tarmac inside the fence. Near the southeast corner of the compound, near a picnic table inside the fenceline, was the obvious highest ground, outside the fence. This point seemed at least as high as the concrete inside the fence, if not slightly higher.
Continuing north along the fence, I came to the NE corner of the compound, near the main entrance. A secondary fence prevented me from following the outside of the main compound, so I retraced my steps along the east and south sides of the summit. The SW corner of the compound also has a secondary fence, but hikers seem to have peeled back enough of it to make a passage. The west side of the compound is tricky, since following the fenceline takes you on a couple of narrow spots near buildings and on a odd stone wall. Once on the north side of the compound I completed my circumnavigation near the main gate.
I feel very confident that I stood on the highest natural ground on the West Peak of Tamalpais, at the SE corner near the picnic table; and that I was at essentially the same elevation as the huge flat concrete surface inside the fence. Anyone who circumnavigates the fenceline should get credit, in my opinion.
My route from the turnout avoids the negative signage at the main gate and has less elevation gain, too.