Even though other people seem to have had no run-ins with the cops or the neighbours, I really wouldn't advise a carefree attitude when it comes to the site. I visited this place during the daytime about a month ago, and though my friend and I had a good 3 or 4 hours to check the satellites out undisturbed, we were greeted with two squad cars as we were leaving.
We parked some distance away from the gate, not really willing to take the chance of being so obvious. As far as we could tell, we didn't see anyone that spotted us as we were walking to and through the gate.
There were 3 cops that approached us as we were leaving, but the conversation was really brief and non-combative. They asked us what we were doing, and we said that a friend of ours told us that there were a couple of really neat satellites that we should take a look at. One of the cops said, exactly, "Well, this place sort of is private property, but, well, there's no more curiosity, right? You guys won't be coming back?" To which we agreed, of course, and then they just let us go.
My best guess is that someone saw us while were on top of the smallest satellite (the first thing we checked out, and the one which is most visible to the surrounding residential area). It's really difficult to see anyone beyond that, and that would explain the long response time and thus the laid-back attitude of the cops.
Obviously this place isn't Fort Knox, but someone around the area doesn't want people going in and out. Just be careful and leave your "ZOMG, I'M TRESPASSING" banner at home.