Used every cleco in the bucket! Attach elevator skins to frame and level, check for twist both before and after turning over to cleco 2nd side. When 2nd side was done and levels checked (this leaves the undrilled flanges of both spars facing up) I match drilled through the skins into those flanges. Initial drilling #40 and then using a straight #30 reamer chucked in drill seemed to make the cleanest holes. Those holes clecoed and then assembly turned over, rechecked level / twist and drilled that side. These flanges were drilled to #40 from factory and just needed to be upsized to #30. All clecos removed so skins and flanges can be deburred.