Ditto on the Robart hinges, the other standard is sullivan carbon rod. No need to make dead straight runs, easy to use & tough as nails.

I used the 1/8" also & the sullivan rod for the rudder- Kept the split elev thingy for now, but added a brace.
The tube is 7.8mm thick so a 8mm hole works great. keeps it from moving around too much but lets it slide easy. Just put a smear of soap on it to help slide
Irish spring works nice, but I just like smell- ivory ok i guess too