NoRacer,

You do much more with a CF racing bike than most. Quite impressive.

You could go with a seatpost rack fine but would likely have to switch to a non CF seatpost. Another option would be a carradice bag (something I have been considering, as I am in the same situation as you).

I also keep my eyes on craigslist for a good deal on a Trek 520 at some point.

-D