If anyone's going to know this, it's you lot ;-)
What's the best way to demist in an older vehicle? If heat's not readily available, opening all the windows and blasting cold air at the screen seems to help, as the mist appears to be moist air cooling so that the water condenses, so keeping it moving is an idea.
Is there a better way, or has technology come up with a mist-begone spray or similar, or did they all just get new cars ;-)