That's the reproduction of some of the ideas exposed above, couple of things:

1) 2 removable halves, joined by "upper bridge".

2) Use balsa sheet reinforced with CF clothing, will use some foam and/rubber to seal any gaps against the cowl.

... needless to say that is a painful and slow process. I am posting the picture of a carpenter's tool that I used during this process. This tool can help those that would like to replicate the inner contour lines of your cowl, very useful.