As this is an International Forum, the concept of Temperature Correction for very cold temperatures is not as esoteric as some might think.
Come up to Deadhorse in Alaska some Winter or any other location at either end of the World covered in White for Months on end.
If you think RadAlt readings matter during an ILS approach, just consider having a Sling Load hanging under the aircraft while doing the approach.
How does that figure into your concepts being put forth here?