What I do, as a trainer, is put up several slides pertaining to this topic. First, I explain what the operator must do should the (sit-down) truck tipover. Emphasize the wearing of seatbelts regardless of how long or often they are on/off the truck.

Show that the forklift has a short wheelbase, narrow tracking width and a high center of gravity, and then compare that to a 'Vette, Porsche, Ferrari or whatever else that does have a long wheelbase, wide tracking width and a very low center of gravity, to the point where one is almost sitting on the ground, and compare handling characteristics.

And finally, show pics of tipovers with the operators either seriously hurt, or dead.

That should put the fear of GD into each one of them.

Likewise, for the stand-up reach. Tipping over, step off and back away.

If a professional, caring trainer shows them what can happen, then the odds of a truck tipping over due to speed and stupidity, will be drastically minimized.