Privateer

As I write a viewer and extraction Tool for PT Boats, my goal is an importer that would allow new models to be used in Game. What is the Official stance for such a Tool? I can 'read' the files pretty much at will now but I don't want to cross anyone. Is a player created Tool to expand this Game OK to work on? BTW? I did alot of work on the GWX Expansion for Silent Hunter 3 so I'm not a simpleton when it comes to modding things.