This project got away from me through the holidays. I've had DC-01 powered off for the last month so I'm pretty sure it is more than safe to decommission it completely and finish this project.

Configure DHCP Failover Between DC-03 and DC-02

• On DC-03 I open the DHCP Manager
• I right clicked IPv4 and navigate to Configure Failover
• I select DC-02
• I set the mode to Hot Standby
• I set the reserve to 10%
• I set up the shared secret

Cool that will take care of DHCP. Now let's migrate the FSMO roles from DC-02 to DC-03.

• I confirm from both DCs that DC-02 is holding all the FSMO roles.
• Move-ADDirectoryServerOprationsMasterRole -Identity "DC-03" - OperationMasterRole 0,1,2,3,4 -Confirm$false -Force
• I confirm from both domain controllers that DC-03 is now in charge.

Hooray! I quickly set up a backup of DC-03 in Veeam so I can call this another completed project and close it out.