Okay, orbinauts, first of all, all y'all are awesome.

I found where I've been going wrong: I referred to the "stock DG" as the DGIV, because that's what Orbiter calls it. I went and downloaded dansteph's DGIV-2, and I immediately noticed that the 40 degree AoA showed a clean, smooth re-entry profile. So the final question is, has anyone actually found a good way to land the stock DG without it bouncing along the atmosphere for a half orbit on the one hand, or coming in at such an extreme AoA that it can't hold the angle, on the other?