I have completed a custom campaign for Freelancer! As far as I can tell I am the first one in the world to actually do this. The next closest thing was "The Corsair Campaign", which was a project that ended on mission 3 and released one of their missions for download.
It looks fun, though you seem to have spammed the Capital ships. While they are cool, having a ton of little ships and med ships in between fighting all over the place gives a much nicer battle scene.
Also, the admins are going to sanction you for that wyrm/nepthys combo soon.