Carbon Copy Cloner should do what you want quite well. You would have an exact up to date clone of your documents. I do this for one tiny folder to back up to MS OneDrive... and I have mine configured to do this hourly. It takes less than a second to run.
You can also set up CCC to keep old revisions if you want (important to protect against inadvertent deletion... or file corruption). It is not a true "roll back the clock" solution like Time Machine... but for individual files, it could be useful.