Cool.
Oh; forgot to mention - Blender3d is an open-source 3d modeler that is somewhat respected (but its interface takes getting used to.)
Vorpostenboot sounds great.
Eventually getting the full roster of naval ships in the game for everything would not only be extremely immersive but also be a valuable pedagogical tool. My main concern though is that any new (custom modelled) units would be visually consistent with the current "SH3 Look" as well as historically accurate.