I took multiple images of the scene, with different ISOs set, up to 6400. I found the files with ISO 400 were the most malleable. Increasing the ISO caused the Kilauea glow to lose detail and blow out. At ISO 400, the Milk Way and stars were dim, but I was able to increase exposure on those areas without adding any more noise than had it been shot at a higher ISO. Ultimately, balancing the cloud glow vs. the night sky was the most difficult part.
With such a high megapixel camera, even at 15 seconds, there is a bit of star movement. As was mentioned, there is definitely some coma in the corners from the lens being shot wide open. If I had more time, I might have played around with some shorter exposures, but I worry that the noise might have increased too much. Because of the cloud movement, and short window of opportunity, it wasn't a good candidate for stacking techniques. Also, I am definitely not an expert at astrophotography. This was really my first attempt in good, non light polluted conditions.
If I had another crack at it, I might try a 10-second exposure with the same settings. I am convinced though, that there is no advantage to using a higher ISO than 400 on the D850. I was able to recover the exposure in post with the same noise as shooting natively at higher ISOs, with the advantage of having more usable dynamic range.
Bookmarks