[Brumos RSR]

I would use an actual axle made from your choice material of those mentioned above and based on the rules of your series regarding bushings and bearings.  I’ve used all 3 in proxies with success but, I also build them as race cars knowing that parts are going to be replaced when the car returns home.  None have been damaged or bent in proxies but I’m also racing non mag so I’m assuming less stress due to less motor rpm and downforce.  

If you choose to use carbon fiber, you must use bushings AND you must pay strict attention to how the grub screws bite into the carbon. Too much in any of the 3 places meaning wheel mounting or gear mounting can create a wobble when done improperly.  You will need bearings for this as bushing will generate wear.  For testing, I have run a Carrera Porsche 917 in a modified magnet class for 32 weekends for 672 minutes without issues this way.