Hi Rob: I use the 3/16th" OD carbon rods with 1/8" ID.

My concern would be how long is the unsupported length of the push rod. The rod (actually a tube) is strong enough in tension and compression to handle mucho load but if it's very long and not well supported, then it will deflect and the controls will get spongy. I would jump up to 1/4" O.D. CF tube if the push rod is much over 18" and not supported some place along its length.

AFAIK,  Tom Morris (and Jim Snelson) use the Central Hobbies CF tubes.  At least Tom probably gets them from the same source.  All they have is the 3/16th tubes.  Their threaded rod ends fit this size for ball link usage.  If the rod is slightly too small ID, then run a jewelers rat tail file in them until the end fits.  Don't force the file, in fact the best way I have found is to put the file in a cordless drill and run them backwards very slowly.  This also prepares the end for gluing.  JB Weld (not "quick set") is recommended for gluing, and wrapping the exterior end of the rod with CF tow, veil strips, or some other reinforcement is also recommended to prevent splitting.  Also, do not lubricate the ball links if you use them.  This system I have used for all size planes up to 60 powered piped ships with no problems.