With some careful editing of two texture files, I have managed to fix this artifact without losing too much of the canopy reflection detail.
To install these new textures, simply put the .DDS files from the attached zip into the FA18's main Texture folder (Microsoft Flight Simulator X\SimObjects\Airplanes\FA-18\Texture).
Enjoy some artifact-free sightseeing, fellow fliers!
[attachment deleted by admin]