Hi Crash, It depends on what type of spinner you are using, I use spun alloy spinners that have a hole in the end of the cone for the retaining bolt & I use a dubro balancer, the rod can pass through the spinner & be set up that way, if you are using a plastic spinner, & have access to a lathe a hole could be drilled in the end of the spinner as long as it is dead centre of the cone, it is true that some are a real pain to balance but it can save a lot of wear on both motors bearings & radio gear, especially with larger props. It is amazing to see the number of people that never balance anything & then wonder why they strip servo gears or have cracked crystals & have bearing failures.
Good luck Darion
Allan