A couple of years ago, I paid a guy to assemble a plane for me. He did pretty much exactly what you are suggesting. It worked fine and that airframe still flies today with that setup (He used Kevlar line for the Cable) The minus is that you are relying 100% on the spring to close the throttle off so you would really want a second option of killing the engine fom the TX (Such as a choke servo or TX operated kill switch).

IF it is simply a shortage of material you are worried about, do you have any small carbon tube and 2-56 or 4-40 threaded rod that will fit into it?
Use some good Epoxy paste (JB Weld is best of all) and glue some threaded rod inside each end of the carbon tube. sort of a poor mans version of the Central Hobbies rod ends.