Chris,TAC confirmed that currently it just won't do what is required in the way we are looking at it.A possible tidy/ish solution they did suggest is to use 'bandwidth qos-reference' applied via RADIUS but they also point out in the same sentance tha...
I've actually asked TAC about htis very thing. Ticket is still open and I am awaiting for a reply. Will let you know what they say, unless you managed to find a way yourself already?