You do realize that even if Vitter wins all the undecideds, he still loses by 4 to 6, right? And Black turnout will definitely be higher than 20%.
With the Paris attacks, many voters are switching to Vitter. In addition, others are probably disinclined to admit they will vote for him due to the media hatchetjob he has undergone. You are also forgetting that election day vote is likely to be disproportionately white compared to the early vote. With all those factors combined, it will be a comfortable Vitter victory in the end.
John Edwards has ZERO chance.
A comfortable Vitter victory? Honestly, if the fact that Edwards is at the point where, per this poll, his worst case scenario with 20% black turnout is a 2 point loss, doesn't show he has better than even odds of winning on Saturday, I don't know what does.
Betting against literally everything except "muh republican state!!!" worked out surprisingly well for you with Kentucky (The fact that Beshear won by fewer than 2,500 votes still amazes me). I'm not so sure it will work out well for you with Louisiana though.