I'm skeptical about the double-layering. It will make the hood twice as heavy. Passing air through the middle would have so much interference drag there would be no appreciable airflow.
For a duct to have any chance at success it should be short, un-convoluted and filleted. Here's an example on a Ferarri that addresses that area of the car. The double walled section is short, but there is structure along the hood edge and across the doors to make it work.