www.thetouringstore.com
Tubus racks w/quickrelease adaptor
there are a couple that work with a road bike style rear brake bolt mount.
seatpost mount racks are no good for a camping load of any kind.
I'd go with a Tubus fly, a pair of small (front style) panniers on it (Ortlieb or Lone Peak or something cheap & light from Performance or REI) and stay in hotels for a 4 -5 day trip unless camping is really really needed or desired. Adding in the camping gear really bogs you down, and then you'll be wanting lower gears on your bike, too.