You are definitely headed down the right path. The easiest way to do this would be to discover all of your devices, create a custom property that will help you distinguish the nodes (Production - Yes/No would probably be easiest for this specific example), and then import your list of devices into the custom properties to set your assignments.
Settings > Network Sonar Discovery
Settings > Manage Custom Properties > Add Custom Property, "Node" type
Settings > Manage Custom Properties > Import Values
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