Here I will describe my setup.

I have a desktop connected to another dual celeron system via ethernet.

The dual celeron system runs sirex after remotely booting via desktop.

It also mounts /render on the desktop via NFS so that whatever the blender files render that goes on to desktop.

When Brender sends a command to sirex running on the dual celeron system, it starts of the command and renders the blend file, leaving the result in /render which is also /render on desktop [NFS]

Since the amount of data passing on the ethernet is not much due to blender rendering being compute intensive than disk i/o intensive, even with a few tens of systems it should work well.

Ofcourse you can have a full system instead of a diskless node like me thus avoiding i/o bottleneck if you wish to.

This is in effect my setup. However there is no necessity to stop there. Infact in a short while I am planning to change the desktop. Then the current desktop will become another node.