Same issue when I had the turbo setup....thought it was going to melt the hood paint. I was considering switching to a heat extractor hood, but I would say start with your heat extraction cut out idea and go from there.

Here are some small things that I did which seemed to have helped my setup:

- increased the size of the plastic rad air dam to try and scoop more air up
- used deflective heat tape in certain areas
- wrapped all my hot piping (more turbo related)
- removed the weather stripping at the back of the hood near the cowl which opened up a gap (95 Cobra R hood)

I also know that some guys remove their fender liners and look at ways of opening up larger holes/cutouts on the underside of the hood to try and funnel the air out.

Its not much, but hope its helps!