Slightly unfair I think as the Panzer girls can't join the Witches and the Kanmusume at sea.
Except for those huge school ships as big as Super Star Destroyers that they cruise around the sea in. Just drive the tanks to the edge of the ship and fire away.
Seika said:
They can fight and hold out the lands though, and provide and home base for the ships and airplane.
Additionally, if aircraft are part of the equation, I imagine that Panzer teams would include mobile anti-aircraft platforms in their lineup. It would necessitate them including the third dimension to their tactics.