Surely a simpler method without coding would be to use the "inbuilt" networking ability of Indi (e.g. chaining).Then ,perhaps using the newer Compute 4 (they have EMMC storage) RPI's, create a dedicated Large Cmos Camera server but using "command Line" Indiserver only (NO GUI,System X) to maximise resources .

The initial capture(s) could be stored on these dedicated Large Cmos servers and transfered in "background" mode so not to effect camera capture speeds. Any conversion could then be done on the "other" Indiserver(s) which would have had resources freed by moving the Large Cmos camera.

I accept this would mean extra hardware (RPI's)/networking(wired hub unless you rely on 5GH wireless) hardware costs,perhaps slower image viewing due to transfers but it would be with the minimal amount of software changes to existing Indi structure - until 64bit drivers are created.

Just an Idea !