Really is a beauty Wayne!
Bl**dy shame about the 'see through' decals. All options are tricky, but I think cutting small strips of white decal, applying these, and, if required, touching-in with thinned, off-white acrylic paint, using a 'damp brush' is possibly the safest solution. Even if you had the spare decals, obtaining accurate register with the existing decal would be very tricky. At least with decal strip and touch up, you'll get a uniform appearance, which, under the gloss then matt clear coats should look more than acceptable.