The sites I want to see next weekend are under private and/or township ownership so I'll just go knock on doors and ask if I can go in. Failing that I'll try to get the best pics I can from a distance.
But it never hurts to ask.
At Camp Hero in Montauk there are also 4 artillery batteries for 16 inchers that had "underground" passages between them. In this case the passages were actually above ground structures covered over with soil and vegetation to look like natural hills.
In fact this camouflaging of stuff was one of the best features at this base. It was made to look like a tiny fishing village. Even the Anti-aircraft bunkers had fake wood siding and trim cast into the concrete as well as actual wood shingle roofs over the actual rooftops. In old time photos of the bunkers they looked like cheerful beach cottages until you noticed the gun slits right under the eaves with 20mm gun barrels sticking out of them.
All this effort to conceal is seen only in the structures from WWII when the coastlines were being observed by U-Boats.
During the Cold War they gave up the pretense completely. After all how do you make a rotating radar dish 135 ft. across look like part of a cutsie seaside resort?