Disguises and provoking faction wars

[BebopCola]

I've been trying to muddle out if there's a way to wear a disguise and engage in shenanigans that damage the relations between two neutral/friendly/allied NPC factions.

It seems that even when sneak is 100, and you have a full body covering of disguise, attacking, even from very far away with an Eagle's Cross, Instantly blows the disguise. Any way around this? It is my fondest dream to destabilize the United Cities by turning the factions against one another.

[Macongula]

I know that if you remove all of your characters limbs you become practically invisible, but it helps if there's nobody looking at you as well as lighting.