I had a toughened windscreen shatter twice in my Austin. One of them was while i was overtaking a lorry. Short term visibilty in order to complete the maneuvre was to stick the head out of the side window by instict. Well, it was summer and the window was open anyway. As soon as i parked safely at the hard shoulder, my next move was to completely remove the broken glass. There was no way i would complete the journey with the shattered screen in place.
Screenless driving was interesting, obviously drove relatively slowly and kept as much distance as i could from vehicles in front of me. As both me and front seat passenger at the time were wearing glasses, it didn't felt too bad.