K4 Mac or PC K4Mac and Amazon Drive (Personal documents)

I know this is a common topic but searching the forum, most of the topics are pretty old.

I know K4Mac doesn't show personal documents and ALL the books on my Kindle Voyage are emailed as personal docs.

However, I googled some old tip about possibly using Amazon drive as a hack.

Except (of fvcking course Amazon!) K4Mac creates its own "My Kindle content" folder in whatever folder I point it at instead of using the empty root folder or Amazon drive's "My Send-to-Kindle Docs".

Has anyone managed to get K4Mac to use a different folder?

I read that Send to Kindle doesn't send books to Amazon Drive now unless I do it manually from the Content & Devices page. But I''m hoping K4Mac can see the personal docs I manually add to Amazon Drive and I can still benefit from whispersync ...