CF pushrods should not be an issue in terms of radio interference. They are light and very strong. The only issue, I have read about, with CF is that large amounts of CF used in the area of the receiver can cause interference. I have not personally experienced any problems and use CF on my fuselages to provide reinforcement. Mostly I use it to reinforce the engine box and other high stress areas. I suppose a fuselage made primarily of CF could cause some interference problems but I'm not really sure.