Anyplace where there is a solidly built castle can serve as a fortress(in the book World War Z
, there's references following the Great Panic to the British using Windsor Castle and Balmoral as fortresses.....)
Adding to the ship inventory...........
~~(hospital ships)USNS Mercy and USNS Comfort(1 in the Atlantic, 1 in the Pacific)
~~(coastal patrol ships)USS Hurricane, Typhoon, Sirocco, Squall, Chinook, Firebolt, Whirlwind and Thunderbolt(to be used in a matter similar to the littoral combat ships)
~~(combat replenishment)if they can be turned into multi-purpose ships, then include these as well....at the very least, they can be used as rescue platforms offshore
~~(other ships)I'd add more, but I think you've got a pretty good list in the previous post
As to the land bases........good suggestions; here are a few of my own.......
~~motion detectors at key points of entry/exit manned at all times
~~defense in depth.....if possible, keep an outpost line along major routes into/out of each fortress....if forced to withdraw, then a second line of defensible bunkers(connected underground by tunnels lined w/explosive charges in event of infiltration)...finally, another set of tunnels connecting those bunkers w/the fortress(again, rigged w/explosives)....each outpost should have a telescope/binocular viewsight to check the area around; also, if anyone has sniper experience, place them in one of the outposts so that they can view the area as well
~~mobile defense.......use whatever vehicles are availables(cars, trucks, Humvees', etc), armor them as much as possible, arm w/light machine guns(SAWs, M60s, etc.) and use them for patrol/reinforcement as needed
~~if there are available pilots, use them to man several helicopters(fully-fueled and armed at all times) on an Alert-5 watch(I'd shy away from jet aircraft and instead work on restoring prop-driven planes instead[again, going back to what was done in World War Z
; they abandoned pretty much every fancy, expensive fighter jet and went back to prop planes and even dirgibles......)
~~again, I'd add more, but those were some pretty darn' impressive ideas in the previous post.....