The DK patrols should not be that hard to kill. If you stick to the south western area, you should be able to take it out without attracting the guards' attention. You can repeatedly sneak close and attack with a bow or magic, then withdraw before it sees you.
If not, try running into the room and then run back out and through the trapped corridor. With any luck they will be hurt or killed chasing after you, making them easier to take care of.