I've decided to build a firewood-specific structure at my cabin. After chatting with the owner of AK Fireplace and a little online research I settled on the pallet shed.
I'll have about $200 total into foundation, metal roof and 5/16 bolts. Pallets are free.
The structure should provide maximum drying while still keeping out driving rain and snow. If the snow creaps through the slats I'll temporarily screw spare plywood around the bottom of the structure for the winter months.
The photo shows the 1st floor pre-assembled in my driveway. It will be a 2-story structure.