I have often recommended against using hi-starts in freezing temperatures, however so many people have related their positive experience with hi-starts in cold weather that I felt I should relate this to you.  I still do not plan to use my hi-starts in freezing weather but I have alternatives.

I have a ford long shaft winch, which is my main launcher.

I also have a OneWinch, www.onewinch.com which works like a winch but has no batter or motor.  You may want to give it a try.