There is a rack like that made by Axiom, i believe, that is very adjustable and cantilivers itself off the seatstays like that trek rack. We sell it at the bike shop I work at. but without that forward hitch design..

Designed for use on a bike with disc brakes, it is one of the most versatile rack mount systems. And pretty stout compared to some of the other hokey disc brake rack design. let me try to come up with the name of it tomorrow.