BBQ.... yes.... Pirates W/B is a tough one. I generally end up shooting at "incandescent" (RAW files) but then end up usually brining down the W/B temp in Camera RAW (2800K?). And.... often times I end up processing or re-processing a duplicate file at a different W/B, sometimes warmer and then blending in PS. There are DEFINITELY some odd, or shall I say difficult color balances going on in there. As far as your W/B swings, I don't generally shoot Auto W/B, I assume the camera (because of the "auto" part) is trying to balance or correct each frame. And as I say and we both know it is a jumble and constantly changing (as you move though) color temp challenge in there. I do mostly shoot my D750 for dark rides, but have a much more complete Canon system. My main body being 5D MkIII which I love, but the D750 does beat it in low light.