I think that there's something that you're missing here. What are you looking for the golden rod to do for you? It does not and cannot absorb humidity. Is corrosion forming at the average humidity level that you have?
Nature hates a vaccum, and every time that you open the door to the safe, fresh air gets in and the humidity level evens out to whatever atmospheric is at the time! If you're not experienceing any corrosion now, be satisfied that everything is OK and go on to worry about more pressing things in life!
Reduction in humidity by absorbing, heating out, whatever, will not replace good common sense storage of clean and well lubricated. If the humidity is going up, likely you need to track what the atmospheric humidity is in your storage location. Unless you have some water in the safe, there's no reason why it should be any higher than the room it's in assuming your safe is sealed and not a vented unit. Heated air devices, like the the rod, work on convection. The heated air has to have somewhere to go or it simply heats up, expands, and can hold MORE moisture. In a non vented safe, the theory is that it will keep that moisture suspended in the air rather than allowing it to condense onto the surface of whatever you have stored, but it will not remove the moisture. To do that, you need an absorber.
I wired two 7 watt bulb night lights into my safes, mostly for lighting. Together, they not only provide light, but work better than my golden rod did, so I ditched the golden rod and wired lights into both of my safes. As added insurance, I have a small container of the Damp Rid pellets in each one. I empty the little bucket and add new pellets twice a year, as they do fill up and work correctly. I live in Norfolk, 3 miles from the ocean and my safes are bolted through a 4x4 platform to a concrete floor in my garage. Since I set up everything this way, I have not had a problem. No rust or any other corrosion has happened in 7 years.
Something that I learned from my buddy of mine. He used to store his rifles bolts closed. After a 6 month deployment, he had some corrosion form in the bores of a few rifles and on a few bolt faces. I deployed the same time that he did same cruise, and did not experience any problems and we have exactally the same safe (Cannon Eagle, 550lbs), purchased at the same time (bulk discount) and live 3 houses down from each other and we oiled and preserved our guns the same day (going away party with our gun buddies), and have the same lights and damp rid pellets. In short, having moisture traps with the bolts closed allowed any condensation to collect with the bolt sealed chamber as the low point. I kept my bolts open as the only difference.
YMMV, but again, if you're not getting any rust, keep cleaning and preserving correctly and stop worrying, you're doing it right!
Tom