1. how will droopy know which books are in which archives in the cloud.
2. droopy's problem is lack of space on his single SSD drive, what happens when there is insufficient space to restore and expand one of these archives from the cloud.
A better solution might be to use Save to Disk to copy the format files of the 'low priority' books to the cloud in an 'Author/Title/' folder structure. Put links to the cloud storage format files in a long text column, delete the format files from the library.
The library would continue to serve as single catalogue. Decisions as to which books to Save to Disk (Cloud) can be made individually (no batching), the books can be Tagged in the database. Format files can be reinstated individually or as a group if they are 'buddy files'.
The 'downside' is that to read a book that has been saved to the cloud one would have to click a link in the Book Details panel and wait for the format to download, but that would be a lot easier than restoring and unpacking archived libraries, etc.
BR
Or droopy could buy a 256GB external flash drive and move his library to that
