Ok, I misunderstood your intention behind the bayonet part, then - truth be told, I wasn't too sure where you wanted to go with it, and so I just answered in the general direction of that topic.
Good to know that your actual riding/horse experience checks out with the current take in period history on cavalry charges. A conservative estimate of the horses' abilities also seem justified by the general supply situation... Max charge distance in the game is 600-900 yards with a 150 yard hex scale, and less accordingly with smaller hex scale. Charging from that far away is more or less pointless though, unless you really need the extra movement to say, flank-charge some unguarded artillery - even if you don't get to 100 disruption in the process, which of course ends the charge immediately, the disruption increase usually more than cancels out the distance bonus.
The earlier "cavalry has to charge x distance" quote probably refers to parade/maneuver, and as an indication that the unit is generally battle-worthy, i.e. able to maintain cohesion on the move.
no truth - no justice
all false belief
blinded by morality
there shall be ... no peace