Be careful attempting to refrigerate additional cubic feet via conduit. The refrigerator may not be capable of removing heat from the this space.
If the refrigerator is capable, a recommendation would be to route the line through a one inch flex tube (placed inside an insulated two inch conduit) all the way to the back of the faucet and then return this air back to the refrigerator via the two inch conduit. Use 15 or 60 cfm blower to move the air. Seal entry point of beerline into flex tube past blower.
Scott Zuhse, Instructor
Micro Matic Dispense Institute