I'm halfway there for the PT on rivers, bridges are making it possible so that you can run a river, canal or channel through a GV combat area.
How to protect an airfield with the maproom on it and no town from GVs? Eventually this will get shore batteries and PT spawns to defend against task groups.

Each country has a PT spawn in the canals at TT.

The view from the canals at TT from a PT.

Three bridges or the equivalent is fair to both sides of an attack.
