Rather than trying to match up to the returning underside of the bonnet, we decoded to cut this off to make a horizontal flange to mate between the valance and bonnet. Bonnet pins mounted to the front suspension mounts now hold the bonnet in position at the front.
Using a plub line we marked out the silhouette of the bonnet, then added 50mm to this, this gives us a maximum projection for the splitter (to comply with RGB rules) and cut it out
We then added the upper parts which follow the lower edge of the now shorten bonnet. This gives a buck to build up a mockup of the valance.