[Big Dave]

Good start. Like the general shape.

Minor quibble: You are too steep. Mine was. I went from the top of the cab to 1 inch above the tail gate. That was about 17 degrees. I had separation, so I ditched that cover and am moving to something different.

The best aerolids keep the angle to 12 degrees or less. That's about a 1-in-5 pitch. Raise your "tailgate" pipes up til you get a 1-in-5.