I,m in North Carolina ,heating rod works great in my safe. It's in the house on a wood floor,no warpage to floor in 4 yrs.I have my safe in the basement. The safe has a heating element in it and I run a dehumidifier in the basement. It stays at about 32o/o humidy. They would have one hell of time trying to get it out of the basement. My safe came with a small hole in the back for the cord of the heating rod. The dealer I bought it from has three safes in his house and uses the heating rods. It works for me.
I have a champion model T with lights and dehumidifier, works quite well. Still a tweaker with enough time can get in anything!Tomato stakes? I put a 28oz desicant can with indicator in my safe 30 years ago. It turned pink or purple whichever indicated time for a dry out in the oven within a week. Golden rod is the only thing that worked. You could use a trouble light or something with a incandescent light bulb (they are getting harder and harder to find these days) and it would work just fine...until the light bulb burns out. I'm sure there are other golden rod type products out there but I dont know what they are. I should probably replace mine but it just keeps working. Very warm to the touch.