You have several choices:

1. Pull-Pull on the elevator and rudder.

2. Custom made carbon fiber rods such as Dave Brown

3. Use Nyrod, well supported (such as Sullivan ). You can join the inner rods by using a piece of the all threaded rod (provided ) and you can join the outer sheath by cutting a piece of the outer sheath about 2" - 3" long and splitting it lengthwise. Slide an outer sheath in from each end and butt them against each other then use thin CA to adhere the cut piece to the 2 sheaths. I suggest staying about 1/8" away from the seam where the 2 outer sheaths butt together. As long as this is well supported you will have no problems.

Pull-Pull will be the lightest, then the Nyrod followed by the Carbon Fiber rods.