Nice render. Although, I'm sure you're, both of you, quite mad!
... I looked at the .tgd you posted and was very surprised to see the quality settings you have used, in both clouds and atmosphere. There are some 370 atmosphere samples (roughly), and with a cloud
quality of '50', creating over 600 cloud samples, it's no surprise that this took so long to render!
I've got to wonder, was it really necessary to use such
extremely high settings to clean up the noise? Especially in the atmosphere, there are very little atmo-shadows involved in your scene. I can understand that the clouds, with all that stretching(500 Y), need to be set pretty high but Q=50?
And, surely '-4.2' is easier to type than '355.873' for sun elevation. After all, it can only be set between -90 and 90 degrees.
I've not tried to render any of it myself yet but I'm paring back the settings and I'll see if it can be tweaked any at my end later on.
It is a lovely, clean scene, though! I wish I had you guys' patience!