Gavin,

Have you considered one of the large bum-bags (or fanny packs as the Yanks calls them)? I think that Lowepro makes a large one.
If you're not intending to add lenses to your Fotoman, you could carry your camera in said bag, but on the front...

This is also a great way to carry your camera on planes. In fact, you can often "hide" the fact that you're carrying it if you also have another carry on bag; just point it backwards when you head to the check-in desk!! (Ken Duncan once told me that is what he often uses when flying).

Lachlan.