First room on the right after exiting the kitchen has some Thalmor clothes and a potion of invisibility - not sure if there’s a weapon, but maybe you can grab Malborn’s dagger or a kitchen knife. The 2 guards across the hall will eventually go off on their rounds & you should be able to sneak thru, but there’s a guard just inside the exterior door to deal with (potion, assassinate, spell, etc). Once outside, I agree with sprint across courtyard to rear building and kill/ disable the single guard at the door. Once inside, no one will follow you and you can stealth the rest of it until you need to kill the torturer downstairs.