Pikachu, I grappled with the same issue - power failure after a hurricane. I use the goldenrod but that's obviously useless in a power loss situation.
The problem with the silica gels is that they absorb moisture and saturate pretty quickly, at which point they are useless.
I no longer use the silica in my safe. Instead, I'm being absolutely anal about cleaning and oiling. A good coat of oil on the guns in the safe will stop corrosion if (when) the power goes out. I'm going so far as to think of putting a drum of a light oil (CLP type) in my garage and dunking whole guns sans plastic/wood before putting them away.
Another thing that will help is to minimize opening the safe in a power out situation -- the safes are pretty close to airtight and opening it will keep down the relative humidity for some time.