I was in this black hole not too long ago myself. Almost the same criteria but I wanted a short barrel. So I went 6.5 saum. If I went with a standard length barrel my choice would have been 6.5cm all the way because of component availability. Now if it was just for hunting, I wouldn't have...
Your biggest concern is your powder choice, do not run staball 6.5 or cfe. (No ball powders). I have had hangfires using both of these with cci 450s in below freezing temps. H4350 no issues at all.
I would look into heated gloves for skiing or motorcycling instead of hunting. Seems all markets related to hunting there's an abundance of highly marketed junk .
I have researched extensively on a pair of heated gloves or mitts. Most every comment or review said the Sitka incinerator. Which is not heated.. but it was mentioned all the time. No heated glove on the market seemed to be worth the price.