Throw a spanner in the works by suggesting a look a the Runbo range of phones. Going by the specs: dedicated GPSr durability, very long battery life, run android OS so you can use c:geo app and load offline maps, fairly decent cameras, and are also walkie talkies.

http://en.runbo.net/productview.php?id=226

Do you know of anyone who has used one of these or reviews?