Hello Darren,
no direct experience with Nexus up to now I see the use of management interfaces on 12000 GSR or similar devices.
They can be used for an out of band separated management network connected to a separate lan switch.
In the case of GSR in rommon the only interface they see is the management interface.
Being a remote site having a terminal server can be wise in order to save a travel to the site in case of issues.
An ISR router even a C3640 or C3660 with A/S serial interfaces can act as terminal server.
The device needs an indipendent way to reach your network, it can be a DSL line and you can deploy a GRE+IPSec tunnel over it.
Or you can have it connected to the network if you have two routing devices in remote site and two WAN links to reach it
It is more common in service provider environment to build a full out of band network.
Hope to help
Giuseppe