And so we did. Scarper Peak, nearby Ox Hill, and the entire route we were to take was on land not open to the public. We had two route choices, both about five miles, one way, though it was possible we might be able to drive partly up one or both of our options. The first choice was a dump road off SR92, and with a bit of trouble initially, we found what looked like the BFI road indicated on our map. Trouble was there was a gate right at the highway that had not been there when the Google Street View pictures had been taken. Rats. This made me unsure that we were at the right road (we were), and I hesitated to commit to it. On to Plan B.
We continued to Halfmoon Bay, north on Highway 1 about a mile to Frenchmans
Creek Rd. We found this road in terrible conditions with large potholes, but
ungated. Concentrating more on the signs and buildings along the road, I
practically ignored the potholes that we took head-on as though we were
driving a tank rather than Steve's Honda (and he still thanks me for
doing the driving, despite the abuse). About a mile up we came to a fork in
the road, both sides gated, and stopped the car out of the way between the two.
There was a home about 50 yards south of us, partially hidden by shrubs. A
light went on from that direction, possibly a sensored security light, possibly
someone coming out to have a look. We saw no one, but it made me very nervous
until we had gotten out of the road and through
the fence on the north side of
the road. Although we had all thought we were ready to go as soon as we got out,
in usual fashion Steve had a few last chores to complete before locking up the
car. Also in usual fashion, his delay caused me angst and I got short with him
in an effort to hurry him along.
Fortunately we've been through this routine enough times in the past that it
doesn't really bother either of us a few minutes later, though it equally does
little to change the routine in the future.
On the paved road heading north, we passed through a large nursery complex. There were lights on in various buildings, a number of cars and other signs of habitation, though no sounds of activity could be heard. One large building had a door open through which we could see a covered table with a bottle on water on it, but again, no movement or sounds from inside. It took about ten minutes to pass through this area, all the while we held our breath and tried to make as little noise as possible with our feet on the pavement. Past the last building the road curves to the right and begins to climb up out of the small valley that holds the nursery. Another ten minutes went by before we felt safe enough to talk, finally relaxed and able to enjoy the rest of the way to the summit.
We commented how odd it was to hear the ocean surf several miles away. There
were other sounds, from trickling streams, crickets, fog horns in the distance,
and aircraft flying
overhead, but for the most part it was pretty calm. The moon shone brightly on
the road and surrounding terrain. Though much of Montara Mountain is forested,
our road wound its way up a curving ridgeline that offered very nice views off
towards Half Moon Bay with the city lights, buoy lights in the bay, and small
lights from boats asea. We came to a 
second gate
that needed to be surmounted,
likely marking the northern boundary of the nursery property. There was a
phone number on a sign to call for access, so while we continued on our way
Steve called
the number to see what he'd find - a recorded message that
the phone number had been changed).
The entire road to the summit was paved, presumably for
service vehicles in reaching the communication towers atop the summit. As we
got higher the road switched over to the more forested north side of the ridge,
offering glimpses of the peninsula lights on that side of the range. It was a
very enjoyable route, we all agreed.
There were a few junctions along the way, both of them within 30 minutes of
the top. The first was with a road coming in from the east, our primary route
option that comes from the dump along SR92. A second junction was encountered
shortly past this, not shown on the map, but we simply kept to the pavement to
find our way to the summit. An hour and a half after setting out, we found
ourselves at Scarper Peak. The top had been bulldozed flat, towers and buildings
errected, and a fortified fence enclosing the whole thing.
A sign indicated it
was maintained by the FAA for air traffic control. Though there was
little need to go inside the fence, I started to do just this at a corner near
the main gate where the 
barbed-wire
atop the chainlink had been broken and most
easily breached. But as I started up a voice sounded from a speaker outside a
nearby building. We paused to listen to the message, but couldn't make much of
it, and whether it was coincidence or set off by sensors we didn't determine,
but I gave up the idea of going inside just in case. We
marched around the
outside of the fence until we could be certain there was no higher part inside
or out, then went back to the gate and back down the road. The summit turned
out to be a disappointment, most of views blocked by trees except for a small
portion facing south.
We stopped at the adjacent 
Ox Hill on our way back, wandering
through tall grass, photographing 
small flowers and
odd equipment we found about the place,
but again, not much for views because of the abundant trees. Our return of
course went back down the same road, going quite nicely and entirely
uneventful until we got back to the nursery. At this time, nearly midnight, we
figured anybody on the premises ought to be asleep and we weren't too worried
about quietly slipping through. Then we noted a second car parked where only
one had been on our way up, and a door to a windowless building slightly ajar
with a light on inside. As we were in the process of passing it along the road
three dogs suddenly came barking, snarling and growly their way out the door
to sound the alarm. A large bulldog, a rotweiller, and a third dog that I've
forgotten the identity of in the small panic that ensued. Yikes.
Steve was in front and continued walking at the same pace along the road looking like he hadn't even heard them. I was second behind him, getting ready to take off on a run though I suspected that would only kick in their chase reflex. Bruce was in the worst position behind us as the dogs gave him the most attention as we went by, the dogs circling behind and coming within a few feet of him before pausing when he turned to face them. None of us said a word, and following Steve's lead just continued walking quietly down the road while the dogs set up an awful racket behind us. We waited for someone to come out, yell to us, somehow let us know that they were not happy with our being there, but the angry human voice never came. Later we figured that being so close to the forest they must get the same reaction when deer wander in, so the owners probably thought we were some form of wildlife wandering through the property. Had we yelled at the dogs or otherwise tried to shush them, we may have gotten the unwanted attention we were expecting.
We made it back out to the car without further incidence, tossed our gear in the trunk and made our getaway as quickly as possible. It was nearly 1a before we returned home to San Jose. Looking back, I can't recommend the route we took because of the dogs - I think we were lucky we didn't encounter them on the way in, in which case we may have turned around immediately. The BFI route from SR92 is a bit longer, but probably quieter and less peopled, and looks to provide equal views both towards the ocean and SF Bay.