I've done it before, but I'm not ashamed of it...
You have to look at the legal issues here... that is, if you
do decide to "get" the guy, which I certainly would never recommend to anyone, of course. Heaven forbid.
But just as a theoretical situation, it would be to your advantage to think clearly and be smarter than the idiot (I mean, cage driver)... for instance, "what if" you:
Give the guy the finger or whatever it takes to get his stupid face red with anger, then race ahead with him in pursuit. Be careful not to lose him.
Find a spot to pull over that's wide enough for his truck... make sure there are witnesses around.
Quickly get off your bike and wait for him to jump out of his truck and rush over to you screaming (if he's not angry enough, another discrete gesture with the middle finger may be in order).
Do NOT take your helmet or gear off. No such thing as a "fair" road fight. Let him take a few swings at you, (make sure there are witnesses) and after he breaks his knuckles on your helmet, you can now "defend" yourself all you want, since
he attacked you first. He'll be helpless with his busted hands, so you can take your time and enjoy it. Just be sure to stop short of killing the bastard, that could be a real nuisance in court.
The witnesses are the key here... all they saw was a crazy A-hole in a pick-up chase you down and attack you. You have every right to defend yourself. Know what I mean?
ATGATT!