The issue with the v4 and extreme cold weather is only a voltage regulator. Back in the day I ran a few v4s and had issues. RJ had found a component that worked in the extreme cold. Sent me a few, soldered them in and all was a good as v5. Did some searching for you but that is many years ago and I am striking out. Fact of the matter is, it so much easier to throw in a c9 (I used a c7) and your good to go. Save the voltage regulator mod for a day when you can put it on the bench... -20F is cold as a witches...
They stopped making that part a couple of years go but I bought a few hundred. But since then sent them all out to people to update their V4's so I have none left.
RJ
