Allan,
Don't use the rayon threads!
Stick to polyester.
There are all sorts of problems with rayon that make it unsuitable for rod work.
Madeira metallic threads are pretty good.

Allan,
On smaller rods, I would stick to size A or even go to a #40 embroidery thread lie Madeira or others.

I often use size C for the wrap thread and #40 for the pattern threads.
On real light rods you will likely use size A on your guides so it makes sense to use the same thread on your weave wrap thread.

Depending on your current pattern, you may be able to simply switch sizes and get the size you want.
If you did you pattern in P2W, just change your two thread sizes and it will tell you roughly how big the resulting weave will be.

Sometimes though, you can get a better result if you design the entire weave with the smaller thread in mind.
This is because you can fit in more detail using smaller thread.  i.e. You have more "pixels" at your disposal for teh same sized weave.