Hi
instructions are good, few notes however:
No need to backup
/etc/shadow
No such directory as /etc/dropbear no need to add to backup.
Add
/usr/local/etc/dropbear/dropbear_dss_hostkey
/usr/local/etc/dropbear/dropbear_rsa_hostkey
to backup to save generated keys over reboot.
I find more convenient to have a new user defined, 'ru' with password and part of sudoers. In this case you can keep tc without password. With new user(s) add
/etc/sudoers
/etc/group
to backup.