Hi Michael
1. You can remove the authorization object form the end user role. who required to release the background jobs those user you can provide the authorization.
Roles and Authorizations Used in Background Processing - SAP NetWeaver Security Guide - SAP Library
2. You can define the Day /Night mode settings as mention in the links
https://help.sap.com/saphelp_nw70/helpdata/en/c4/3a5e5c505211d189550000e829fbbd/content.htm
Step-by-step procedure to set Operation Modes in an SAP system
3. Inform users to release all the background jobs in off peak time, not on during the business hours
Regards
Sriram