Tailgaters can tailgate me all they want. When traffic is heavy
in front of me, I will keep 3 to 4 car lengths. Or slow down until
tailgater over-takes.
Before braking, I would always turn ON hazard lights for 2 to 3
seconds, indicating slowdown in front so that tailgaters or traffic
behind me is alerted. To shake off tailers, I would purposely
switch into a lane or get behind large and slow moving trailer
trucks or lorries. This usually spoils tailers "fun", and they go
away. Or, if there is NO traffic in the middle lane, pull out to
the center lane suddenly and jam brake. This causes the tailer to
over shoot me, and I cut back into the left lane directly behind
the tailer. Of course keeping good distance.