I agree. As good as Victron equipment is, having the temperature sensor internal to the 100/30 is stupid. Should be at the end of a 10 ft wire so you can put it on a battery or at least in your battery box.
You may want to find a controller that more suits your set up and has a remote temperature sensor.
My 100/30 is right next to the battery box but no issue with a close by furnace.
What river(s) in Alaska did you do? I lived there 42 years….