I don't think the turrets are too complicated.
From a 3D modder's perspective, they're almost like any other turret.
It just takes 2 additional meshes: One "cover" mesh to close the fuselage in case the turret is retracted, and one "mount" mesh which holds the turret in open position (that 2nd mesh needs to be skinned on both sides because it rotates when the turret retracts).
A Java modder would then have to rotate the mount mesh and make the cover mesh slide accordingly. No big deal.
However, the current 3D model we have is a "Featherweight" config, with all remote turrets stripped. We only have the nose and the tail guns.
Mike