I start attaching the skin to the top of the horizontal stabilizer, and it just didn’t want to line up. The distance between the front and rear spars was too much to match with the pilot holes on the skin.

Noticing some gaps between the ribs and the spars, I took everything apart, cleaned it up, deburred everything, and put it back together. It helped quite a bit, though the skin was still really tight and required a lot of force to get it aligned and clecoed.