Always best to pull over into another lane when appreoaching emergency vehicles, the law in many places now. Was there police presence from the prior accident? Hard to imagine tow-truck ops being abandoned by the staties, especially on the high-speed side. Seems to me like the tow-truck driver should have put out flares in the absence of police support. Some blame is warranted there albeit of little help if the oncoming driver is out of it.
> I doubt a vehicle approaching from the rear has much of a
> chance of hearing a horn aimed forward of the tow truck.
Agreed. Had I been that driver, I would have focused
on getting out of the truck and diving over the divider.
Horn is useless in that scenario.