Thats interesting, becuase I was playing Arma 1 at a friends place the other day, and in the editor you were able to view all the islands. Before you started, you selected the map you wanted, i.e. Sahrani, and then zoomed out and you could see and build on all the islands...for example:
We built an air base om Ramadi and flew to the main island for an operation.
EDIT: Oh...okay. Its just a shame becuase I there isnt any Island vs Island stlye of map.