Maintain Aspect Ratio while Cropping Thumbnail

Sometimes my clients need to reposition the thumbnail to show the subject of the photo which isn’t always center.

So I use Edit Image > Crop > Apply changes to thumbnail > Save but we have to enter the resolution/ratio every time, then shift+drag a corner, or else the thumbnail will generate to the ratio of my crop selection: different than my ratio set in media > thumbnail size by few pixels. (& in settings media, thumbnails “Crop to exact dimensions” is checked)

is there anyway to either a) get the focused/selected crop to adjust itself to my thumbnail ratio on crop > save, or b) a way to “lock” the ratio to the thumbnail ratio when “apply changes to Thumbnail” is selected ??

(I know it’s not a big deal to enter the resolution while cropping, but my client thinks it is because the resolutions and ratios are usually weird and hard to remember like 87:153)