You may have to remove some of the intake components/heat shield to get to the back plugs. You can get a spark plug tool that is a flexible spring that usually fits on a ratchet. It allows you to go around parts that are in the way of using a straight ratchet extension.
I am putting a diagram of the intake in this post so you can see what you would be dealing with if you remove it. I don't think you will have to go this far as you can remove part of the air intake and a heat shield and it would help to have the flex extension, and you should be able to get to the spark plugs.
Before you try to remove them, soak the spark plug in its recess with WD40 or even better is PB Blaster.