I agree with that.
That was my first thought: just open them up, which will probably look fine, particularly in this case where they are body color, but I am working on an insert for the side fins. IIRC It would be more prototypical to the real car and some were left natural metal, some painted body color, and some painted black. Second, the fins overlap one another to a small degree, which cannot be done by simply opening them up. They were a little inset, too.