Okinawa is roughly 100 km long and 10 km wide with a surface area of 1.200 km², so not sure I'd call it "tiny".
Military bases and ranges are big.
I'm not denying that military bases aren't large---although I'd be willing to argue that the land is used quite inefficiently---but trying to pass the Navy's single largest weapons test range, or the Army's consolidation of 3 bases into 1 as somehow representative of the median is absurd.
Firing ranging as defensive depth and simply space to keep people, eyes and ears away from training and equipment.
There are military installations in urban areas that use space effectively but a big spread out base is effective for its intended purpose of preparing to wage war.