I also fell into the trap (back when I had an active Dropbox account) of using the Public folder and sharing links from there. At some point along the way, Dropbox started allowing one to share single files from any private folder without exposing the rest of the folder to the audience, and I started using that method instead. Still, even if I had stayed with Dropbox I probably would have some orphaned /Public links out there somewhere, thanks to this change.

I think we both could have avoided that trap by setting up a small storage VPS with a provider like Digital Ocean or Vultr and installing a document management system. It would still be fairly anonymous; a truly determined detective could find the owner but it would likely require a subpoena, which Dropbox would have been vulnerable to as well.