re: Which loss to Tulane was the worst: 79, 81, or 82?

None of them...the worst was 1973.
Tulane won 14-0, beating LSU for the first time since 1948.

I was there at Tulane Stadium. It was a nightmare. Tulane fans swarmed the field after the game. It was like a bad Mardi Gras scene. We played horribly and were never in it. The game should have been played in Baton Rouge, but then-AD Carl Maddox had botched the future LSU schedules and realized he had too many home games in 1973, so he flipped with Tulane and the Tigers played in New Orleans in both 1972 (we were lucky to win that one) and 1973.
Coach Mac never forgave Maddox for that.

Next worse has to be that '82 game in the rain (at Tiger Stadium!). That Tulane team had no business beating an LSU team headed for the Orange Bowl.