Can the Cluster Box interconnectivity be IP-less?

I have a project that would benefit from having a premade hardware setup for clustering while avoiding the IP stack. Would it be possible to use the PCIe connection for a custom networking stack? Key concern I’m thinking of is if the Cluster Box doesn’t provide a low-enough level interface for communicating to the other boards, that could complicate or even prevent anything custom.

Sorry, the Cluster Box does not support PCIe connections for implementing a custom networking stack, nor does it provide interfaces for communicating with other boards.