Hard to say straight out the gate, so lets go back and forth a little to get a better understanding of your needs…
If the RIO is not doing much in the way of machine control, then perhaps there is no need to be running Node-RED on the edge, just use the native groov Manage Data Services to move the I/O data to your Linux box via MQTT or Sparkplug.
You would need to install Mosquitto (A simple
apt-get install mosquitto) on that Linux box, but since you have a few apps already on there, it should not be an issue.
If your control needs are simple, then you could even send your edge write commands back via MQTT (remember, the tag path is slightly different) and that way the edge RIOs would be super fast and lightly loaded.
If you can share what sort of layout/network/machine control needs you have, we can brainstorm some other options or firm up the options you do have.