Does ubuntu have groups? make a user in the group caddy… Caddy:webworker or something like that. Give that user terminal and SFTP access and add files that way. put a step in your script that asks the script/droplet user to add a password and set up the user account and SSH/SFTP keys… put a blurb in the script for the user to know that if they add files with the root account, then they need to chown -R the root folder.
The droplet user shouldn’t be doing data work with the root account anyway… just sloppy and asking for cowboy errors, right?