Hi Courtney – welcome to the forum – two things:
– from what I’ve heard the ProRes does a little better than CDNG in the highlights.
– in a case like the shot you posted, where there’s lots of highlights and not a lot of low end, I’d consider increasing the highlight sensitivity of the camera. It won’t increase the overall dynamic range of the image, but it will allocate more processing power to the highlights. If you’ve seen my review of the Terra 4k, there are a few shots from a boat in Norway where the frame is dominated by clouds (almost no blacks). For those shots I shifted the highlight sensitivity to its highest setting to capture all of that pillowy soft detail. Something similar might work for the conditions you showed.