How to hang sheet rock when studs and other mount points are uneven. Pictures included.

Howdy y'all.

I framed in my back porch, added windows and such and am now installing the sheetrock on the inside. Because of the way in which one wall was framed in (to make it flush on the exterior), there is of about 1/2" between the studs and the stuccoed sill above the framing. These pictures describe what I'm talking about...

http://imgur.com/a/oyxK0

Frankly, the only solution I can think of is to add some ripped wood to the studs to bring the wall out to become flush with the sill. But I'm wondering if there is some other technique that you construction guru's know of?

I have a coffee can full of up-votes, so thanks in advance!