N280 at Sand Hill
So I took a closer look today, and the hiding spot is on the offramp part of Sand Hill on 280N, which is a lot farther back than any of the other hiding spots I had previously seen. There are a couple huge bushes which do a very good job of obscuring anything behind it -- I don't think you'd be able to see the cop at any reasonable speed you would care about seeing him at.

The downside for the cop is he would have to potentially wend through offramp traffic to catch up to any speeder.

Also today, I saw a cop on the closed (ie middle) vista point in the 3 vista point exits before 92 (also northbound). He was out of his car with a radar gun. Further down the road at about 1/2 mile intervals, 3 people had been pulled over by 3 cops, 2 motorcycles and 1 cruiser. I also saw a pacing CHP going southbound somewhere around Woodside, and a stationary one fishing north of Daly City also in the southbound direction.

Though not consistent, overall CHP seems to be cracking down on speeding a lot more on 280 these days.