And the final follow up for anyone trying to put a quick-release trunk bag on the back of their Juiced CCX. The Topeak MTX did NOT work. It sat too close to the seat with no remedy from Topeak. HOWEVER, the Ibera PakRak DID work. Out of the box, it too sat too close to the seat, but if you email Ibera and send proof of purchase for the rack, they will send longer mounting arms which puts it plenty back from the seat. Alas I have my quick release bag solution.
Thanks so much for your help
@KLee. Really appreciate the time you spent and the inspiration your solution gave me.