Have you thought to use a minimizer to view your fabrics with? In some unusual prints you may be able to discern or infer mtn ranges or lakes. I have found fusible helps to "create" islands, you can blend your several fabrics to mold the islands. Then too.....you could do a series of smaller map portions that show the islands individually... showing off the feature that set each one apart....more maybe but then you could really play with fabric ( the best part)and showcase the islands... just a thought. You could always use fabric pens to write the island names in giving it a little bit of a calligraphic twist like in map designs as well. Would love to see when you finish.