Well, with an ARF it's a moot point, you get what you get and the geometry is going to be off. When I first started using pull/pull I hadn't heard of ackerman and always had slop on one side, like a lot!! The planes flew just fine but I did notice that when I was on rudder turning one way there was a lag when going back to neutral or the other direction, stands to reason there is no tension pulling the rudder for a while. Setting up the geometry is an art and time consuming but worth it on a good stunt plane. If there is slack in the line then the wind is just blowing the rudder back to neutral, not servo tension.
The OP just asked about keeping the wires from rubbing and the best thing I found to keep my fuse from getting sliced is the yellow Nyrod. I make up my systems using braided stainless steel wire fishing leader, it comes in a lot of different weights and I buy rigging couplers to attach it all together.
I start setting up the ackerman during my builds while I can still get at everything, something you just can't do well with an ARF.