For the strong box; Damp Rid Bags, Damp Rid Bags, Dessicant, and more Damp Rid bags.....Keep is as dry as a popcorn flatulent event.
Tack and boot shops also I believe used to have leather soap and/or deodorizer(s), which help.
Dry, dry, dry,....like a desert. Also put some Odor Eaters in the safe, like for your shoes....wipe it down on the inside, Mr. Clean works fine. If you have carpet at the bottom of the safe, shampoo/deodorize it.