An apparatus such as a domain proxy implemented in an edge cloud of a private enterprise network includes a processor configured to aggregate traffic for Citizens Broadband radio Service Devices (CBSDs) in a private enterprise network. The apparatus also includes a transceiver configured to monitor communication with geo-redundant instances of a spectrum access system (SAS) that allocate frequency bands in a shared spectrum to the CBSDs. The processor is configured to instantiate a local SAS in response to the geo-redundant instances of the SAS becoming unavailable. The local SAS is configured to respond to heartbeat messages from the CBSDs. The local SAS is also configured to attempt to establish a connection with an environmental sensing capability (ESC) in response to the geo-redundant SASs becoming unavailable.