Rheinland could use more Unioners, LWB and Bundschuh (especially Bundschuh, they seem to be dying out badly). Bretonia could use more Gaians. Kusari and Gallia could use more people in general. Liberty definitely doesn't need more people, it should lose some. Same goes for the Omicrons (Gamma, Delta and Alpha included).
Seriously, you want to make a faction and say "all else are taken", no they aren't. I would say rather than trying to make a Sirius wide ZoI independent pirate battleship faction (which pushes about all the buttons that it can on people here), get yourself comfortable with one of the smaller factions who do not have a big presence.
Why? Because there honestly are more than enough Outcasts and Corsairs on the server already, and it is getting really boring by now... especially since your faction wants to do the same thing as about all the other factions of that NPC group (Corsairs and Outcasts)... so why not join one of them instead of making your own?