In 1986, I rented a bicycle and rode out to the site. There were heavy piles along both sides of the bridge so that no car could ever again drive off and heavy chains across the approaches so that no car could get onto the bridge. I came to the same conclusion about Fat Boy that you did.
I drove out there around 2005 or earlier. I believe it was before they had rails and cars could still cross to the other side where there was an air pump to refill "flattened" tires so cars could drive on the sand. It was clear what happened, quite obvious in fact. A drunk drove off the narrow wooden bridge in the dark, perhaps distracted by "play" with the blond as he eagerly attempted to get to the beach for sex.