The easiest diplomatic way I see here would be the following:
QCP stop shooting around in the NFZ areas, arrange a deal so you can visit your bretonian friends on the surface and have the occasional tavern brawl with corsairs.
QCP can pirate anyone in O-49 or any Omega system (as per their ID) as long as it is pirating, not blowing up mobile freeports, battleships and destroyers... they use up maintenance resources the Zoners could otherwise trade with :P
Any capital ship guarding a trade convoy outside an NFZ would be fair-game.
Zoners won't like it, but won't be going after them if they stick to doing their thing at least 5 klicks away from Freeports or GC and don't chase ships into the NFZ. All it takes is proper planning where you intercept a trader.
Any Zoner starting to whine about the QCP after such a deal deserves what he/she/it gets.
This would leave the door open for some fun Convoy ambush events which both sides can enjoy.