Well... I need to know what I'm mapping.. xD and I need to know where the connections will be so I can leave space in the map to add the connections in the first place.
hmm... Your doing Altomare? I mapped that for Alizée Jacotey earlier, so... my guess would be tiles relating to canals. But there really aren't any good ones, so I'd try and use the normal FR tiles as much as possible, since nintendo did a good job on them.