I'd certainly call it a big deal when, as the OP says, people are pulling into his driveway several times per hour, it makes his dogs start barking, and it happens frequently at night so strangers are shining their headlights into his living room. That would drive me absolutely fucking nuts.Maybe I'm alone on this but is this really *that* big of a deal? I get that it's annoying, but people do this all the time everywhere.
Sure, I'll occasionally use someone's driveway entrance to turn around, but I avoid it if there's an alternative. And I never pull more than a few feet onto the driveway apron and sidewalk, which are public property anyway.
Oh, and just to be an anal-retentive nitpicker, what we're talking about is called a three-point turn or Y-turn, not a U-turn.