The answer is simple get out of the way; don't you know idiots have the right of way?
Actually it truly amazes me when someone in a compact car tailgates me. Are they trying to intimidate me into getting out of their way? I understand you might think you can if you're following my wife's Civic (and in her case it probably works) but a pickup? Heck if a Prius runs into me I might not notice but I'm sure they will.
I knew someone years ago that rigged a special switch to turn the brake lights on without activating the brakes for tailgaters. I'm not even sure if you could do that to a modern car. A good set of backup lights on a separate switch might be a disincentive.