Yeah I went for the golden hour but as I said the cloud gods were against me. I don't know what it is about that part of the Derbyshire but every time I've been thick cloud's rolled in just before the golden hour
I'm not sure if/when I'll go back as it was quite a sketchy climb to get there tbh.
According to the manual 14 bit lossless compressed files are 28.2mb on average. That means you should get roughly (64000/28.2) 2270 photos. There's no need to use uncompressed when Nikon have such a good lossless compressed.
As for the cards I'm not sure where you're getting that the XQD 64GB are 15 times that of an equivalent SD. When I've looked the XQD's are roughly the same price as equivalent speed SD cards. I got a 128GB Sony XQD card for £130 when I first got my D850, although to be fair I haven't seen them that cheap since. The flash centre have 128GB for £169 and 64GB for £99 if you don't mind the slower Sony ones? I've not used the flash centre before but a quick google shows it gets 5 stars on trust pilot
https://www.theflashcentre.com/sony_128gb_m-series_xqd_memory_card.html?search_string=Xqd+card
TBH I can see the reason for XQD and eventually CFexpress, they're more reliable and capable of faster speeds. My only gripe is that they don't do slower versions for the budget minded. I've never had an issue with the Sandisk Pro Extreme SD cards at 95mb/s, if they did an equivalent XQD that'd be great for me.