Hi,
I lived in San Jose for many years and just wanted to point out a couple things because I think there may be some confusion.
I have seen several references to The Summit and also to Highway 9. For those not familiar with the area, those are two completely different areas. Both Highway 9 and highway 17 go through the mountains, the summit is on highway 17. Highway 9 goes from Saratoga (upscale suburb of San Jose) through several towns - Ben Lomond, Brookdale, Boulder Creek, Felton, and maybe another that would be considered in the mountains. But from what I can recall, those areas were commonly referred to by their names, I don't recall it being called the Santa Cruz Mountains, even though it technically was.
When someone said Santa Cruz Mountains, they usually meant the Highway 17 side, where the summit is. I can't say how it was in 1977 because I wasn't there yet, but the San Jose area at that time was just another place, it wasn't Silicon Valley yet. When I was there in the late 1980s I can remember highway 17 being a huge traffic jam with Santa Cruz people commuting to San Jose for work and San Jose people going to the beaches in Santa Cruz. It doesn't strike me as a place one could stop to dump a body unless it was really late night/early morning. Highway 17 was also a dangerous highway, lots of twists and turns that sneak up on you and no divider separating oncoming traffic. Lots of accidents on that road. So even late at night I wouldn't dare stop on that highway.
I would think highway 9 would be a more preferable place to do something like that as it does go through several towns and there are lots of places to stop. But I think if it had been highway 9, they would have said she was found in Felton, or whichever town, not the Santa Cruz Mountains.
I know this doesn't answer any questions but I mainly wanted to point out that the summit and highway 9 can't both be right.