I'm not sure what good having them restored as user databases does, unless I'm missing something?

All my databases, including system, are backed up regularly and stored in several secure locations (one of which is the DR server itself) so I have that covered.

I'm mostly concerned with ensuring that either the following items exist or can be easily created in the event of a need to failover to DR:-

Logins with relevant permissions

Keys (the database master keys are encrypted by the service master key) - these are all backed up so can be restored

Certificates (some logins are owned by a cert) - all backed up so can be restored

Server scoped triggers

SQL Agent Jobs

If I restore the master and msdb databases onto my DR server as the master and msdb system databases, will I be covered, or will it be fiddly to get it all working? If the latter, I guess having a script regularly generated that will create them all is the way forward?