Just looking at the pic's, I noticed the spoiler overhangs the bootlid by what appears to be 20mm and is somewhat square on the edges, I am only making a suggestion but, would it look better if you moulded the edges to 'fall' over the sides of the boot and finish in a sort of point slightly forwards. Agood example of this on a vx commodore clubsport, I will try to find a pic to show you better. This presents anoth problem though, you can't really fibreglass yet.
Note: This is only a suggestion, if you or any other member doesn't like it that is fine, afterall that is what a suggestion is.