Backup of internal and SD storage via script (USB)

**tl;dr** - I want to backup my internal storage and SD card contents when connected via USB cable - due to potentially large amounts of data I don't want to use WiFi-based programs - failed attempt at using rsync and gvfs Is there anything I can do? **Full story** I would like to backup data from my Android based phone (5.1.1 that is currently). I do not want to use an WiFi-based unstable and insecure hacky solutions with SSH and server here and client there (you name it - actually Samsung's very unreliable kies software made me think that way). By now I used a current Linux Mint (18.2), I tried to read data from the phone using rsync and the mapped storage from gvfs which failed miserably (permission issues, unstable connection). I would like to script which directories I backup and automate that process as far as possible. Can I make Android act as some sort of virtual device on Windows/Linux that allows some sort of file based access? Or a Web-DAV server connected via USB cable? No free cloud solutions (Google, OneDrive, Dropbox), either, please! Thank you for your help.