PBJ, I wonder if a Hayes handle would fit? I doubt there's a way to carve it down like a wooden one ... though I guess a materials fabricator could do it. Could be an interesting experiment though.
Hayes company describes the handle of the next generation this way: "...a 16" handle made from practically unbreakable black Acetal...". I'm not even sure what "acetal" is. Is it carve-able? How would it attach to the head? (I have no idea; just curious.)
Ross, I think I might approach a wood worker type person and have a nice handle custom made out of some oak, hickory or birch (I'm not the one to suggest which wood would make the most durable handle, but just suggesting some hard woods.) Couldn't be to expensive, especially if you were willing to do some of the finishing work ...
I dunno, just thinking out loud.
Nem