Probably cheaper to use a heating pad (already has a built in thermostat) and a “safe” enclosure to put it and the spool(s) into… hmmmm…
Keep your extinguishers handy and check their expiration dates!
Fun fact: I kept an extinguisher handy when I flew large scale gas RC years ago. Never had to use one in 15+ years. More recently flying LiPo electric planes/drones… 2 battery fires in 1 year… (both in LiPo bags inside a 50cal ammo box).