I understand the maths presented, but in practice there is no discernible wiggle in an eight for a cox to correct, and it would in any case be impossible to use the rudder productively to do so. The same is usually true of a four as well, although obviously in a pair the asymmetry is more significant and the turning effect can be more pronounced. I also don't understand what is meant by the rowers in a coxless boat trying to cancel out any wiggle by 'counter sideways movements'. What movements?
I think this is generally more of a theoretical problem than a real one. What we can be sure of is that if the various rigs advocated here conferred any material advantage in practice, every crew would be using them. (Which they don't.)