At last, thank-you! Can't pull over because you can't fully get off the carriageway and therefore put other motorists at risk - if you keep going at (say) 50 km/h looking for somewhere to pull over you're doing exactly what both truck drivers were doing anyway.
P*ss poor narrow highway with no shoulder at all, nowhere safe to pull over...That seems to me to be the root cause.
Apply the Substitution Test; how would you have reacted in the exact same circumstances, doing your best to ignore your 20:20 hindsight?
I honestly don't know how I would have reacted given those incredibly difficult circumstances. South Australia is full of rubbish narrow main highways with totally inadequate shoulders, intersections not clearly marked or signposted, lack of safety features.
We should have made more of a concerted effort in this state to keep bulk freight off the road system and on rail.