While I am not old enough to have actually seen this....
(I have seen pictures of it in a Santa Fe museum of old cars backing up the big hill on what would be 25 from Albuqurque to Santa Fe...)
I can remember my dad telling me that if I could not go forward up something and had to get to the top to try reverse. That it was the lowest gear in the box.... seems that if one took it very slow and listened to the toad for any " croaking sounds of death " it should at least be worth a try....