Yes, we can set a cron job to get the nightly backup file transfered. However, 8.2.3.x is already out of support and i would suggest moving to latter code, where we already have this(transfer to FTP) as an option in the menu.
I dont see an API in the guide for fetching the switch config alone.
------------------------------
Vishnu Mannil
Aruba ERT
If my post addresses your query, give kudos :)
------------------------------