This may be an unusual approach but nowadays.......If someone consistently drives too close to my rear bumper, I wait for the next safe opportunity, pull over to the left and let them pass, so they can then annoy someone else.
My theory is that these people have clearly had their brains removed without the aid of surgery so they are unlikely to be using their powers of observation and anticipation and hence are more likely to destroy my car and occupants. This also means that I remain in a calm and relaxed state (well sort of).
Some people do it through sheer incompetence and not necessarily to make a point (this doesn't make it any better).
It tends to happen more when I am driving the old Toyota. As my wife has a spine full of screws (exaggeration....well 8 anyway ) I don't really want anyone crashing into us..... in an ideal world. However, I would do this even if I was in the Jag or anything else.
In days past, in a Caterham 7 on a B road, it didn't seem to happen as often.
It's reminded me of something else. My father (sadly missed) was Head of East Surrey's police traffic department. His advice to me as a new driver was "if someone signals left assume they are going to turn right".