Sorry to hear of your mystery...after all that effort...I feel your pain!
If everything had remained the same (dev, film, shutter, dark slide), could you have loaded the film backwards in the film holder? Were the notches in the top right or bottom left? Maybe there's an Apugger out there who knows what happens when you try to expose through the anti-halation layer.
It will one day snow again and those lakes are going nowhere.