I am from the southern end of this route. Was born down there and spent a lot of my life in the Empire/Buras/Boothville/Venice area. There are some smaller roads that are more bike friendly besides the main highway that could give you options, but you will have to get on and off it all the way to Venice. The main highway is very high speed and can be dangerous.
Another option is there is a road on top the levee system. It's shell and rock, but you can see the river. It will be hard going on a road bike.