I've been playing around on this and I think the route I'm going to go down is a combination of the suggestions you've been kind enough to offer.

There'll probably be three saved scenes; each with maybe one or two cameras and some movements saved as clips in the Trax editor (then destroyed from the original keyframing line).

Not ideal but at least it should work; and I've lost some of the feelings of desperation I had when I started.

Thanks guys.