From Mike Rush who was there when the pic was taken:
1975, Mel Stausenberger, WSA. I'm pretty sure it was Memorial Day, May 75. He did a foot plant off that jump. I was standing a few feet away from the person who took the pic. Crashed straight down like a ton of bricks, I think he tried this twice. Mel was about 6' tall or taller so he was pretty high up. It was insane, I'd NEVER had seen anything like that at that time.
And as far as the shoes, well, I don't know if he did it for the same reason, buy we used to duct-tape our shoes for cornering like the old motorcycle flat track steel plate guys. Cheesy now, but moto back in the dayguys