On a good day (!) I might end up with a similar sized file (2100x1400) as yourself with similar subject matter - although unlikely to be so nicely filled
Better days see 2400x1600 ... and those 'one in a blue moon, going downhill, assisted by following wind' days ... might even see a filled frame that doesn't need cropping
<< 40% crop meaning 60% of the original image was retained >>
... although, in area terms, keeping .6 x .6 (0.36), means throwing away well over half the image information / area (0.64).
Thanks again for the clarification.
pp