There is really only 2 ways to maintain this Sync'd status.
1- Externalize your database. If you externalize your database, then both the Prod and D/R box will use the same data during Production and/or Disaster Recovery Use. Thus, allowing you to maintain the same status for each user on each system. This would be easier using Data Replication for the database used between the Production site and the D/R site, but it's not mandatory. The key here is that only 1 GAService can be active at a time, otherwise ... database integrity could be compromised.
2- On a nightly basis, after internal database backup, you could FTP/Copy the latest zip file from your Production System to your D/R system and have the Database Replaced on the D/R system. This means that if your system needs to be switched to the D/R Server, it would be as of the last restore not as of last use change.
A cluster license would allow you to handle this situation easily, but keep in mind ... a DBA is needed for any of your External Database maintenance and replication.
Some planning is necessary, but the end result is very obtainable.