If it happens in my car, I sometimes switch on the hazards for a few seconds. And sometimes they get the message. If they don't, not a lot you can do, apart from the suggestions above.
One of my worst experiences was in the USA. Driving after dark, I was ruthlessly tailgated for many miles: when the perp* finally chose to overtake he did so at a far-from-safe stretch of road. I briefly flashed my headlights at him. He then came to a standstill a short distance ahead of me, and that was scary! (this being America, was he perhaps carrying a gun?) I stopped and waited. But after about a minute he thought better of it and drove off.
As regards the link in the OP and the 'dangerous loads' theme: I go back to the time when I was living in Bradford many years ago. In those days there was still a thriving wool trade and you often saw flatbed trucks laden with wool bales plying their way around the city. You must understand, these were
big bales, I think about 200Kg each, certainly too heavy for one person to lift.
One day, cycling, I came upon the scene of an accident. One of these lorries had shed its load of wool all over the road. Luckily there were no injuries. If I'd been a minute or two earlier I might have been under one of those bales. Doesn't bear thinking about.
At least, if that had happened, you'd have been spared pages of drivel from Yours Truly....
*Just in case you're wondering, no it wasn't
this guy....