Now, if I had to play by those House Rules I would have been slightly disturbed if a Port unit was put on the Battleboard and fired in every round. Not even AA guns fire in every round, and I know there are attacking aircrafts in every round. After the first round, all coastal guns and blockhouses should have been by passed. Or do you claim that the German Coastal Guns in Normandy still fired at Allied units in St. Vith or Falaise after 3 months of combat ?
I think, IMHO, that rules for facilities like Ports and Airbases, should be as streamlined as possible, to keep the rules simple and playable. Not every casual player you meet is a history buff or have served 5 years in the military. They are not even skilled or brilliant, but play just for fun, or the love of plastic miniatures.
All facilities got inherent AA guns that roll preemptive against aircrafts. Lets keep it that way.
Most major Naval Bases also had close area protection, like sea mines, torpedo boats and coastal guns. This was true to Pearl Harbor, Taranto, Corregidor, Singapore, Sevastopol, Gallippolly, and all ports in Normandy, like Cherbourg, Le Havre, Dieppe and so on. And this is the reason the attackers used waves of air strikes before they launched the amphibious attack. An operational Naval Base should have a strong defense, maybe preemptive since its hard to stay fighting after your ship is hit by a mine or torpedo. But of course there are just so many mines, torpedoes and shells.
So my suggestion is, a Naval Base can roll preemptive up to 3 dice, with 2 or less as hit, against invading land units. Against 1 infantry, the NB roll one dice. Against 3 infantry, the NB roll 3 dice. Against a stack of 20 land units, the NB still roll 3 dice. And the NB should not need a friendly infantry to do this, like YG suggest, because the coastal guns, AA guns, barbed wire, minefields and blockhouses are operated by a garrison that comes with the NB, and not by some visiting Panzer Division that happened to be in the area.
I don’t know how much the NB can participate in a navel battle. Before an invasion, the naval battle usually take place far away from the range of coastal guns and torpedo boats. But some times the fleet is at port, like in Pearl Harbor and Taranto, protected by the facilities coastal guns, minefields and torpedo boats. That why the attacker used air strikes in that cases.