My second stacking solution which I came up with to increase capacity.
6 locust posts about 1meter/40" deep in the ground. Their ends were soaked in engine oil and prior to digging them in plentifully covered with grease and wrapped with PVC foil.
Concrete blocks on the ground and wooden pallets atop of them.
I got the locust from a neighbor for clearing a creek bed, everything else I had laying around unused.
Further future "upgrades" will include steel wire connecting the top of the posts to keep them from bending apart (although, this doesn't seem to be an issue right now), and a coarse steel mesh on the sides to keep the split wood from slipping out.
This stack is currently covered by some PVC foil that already fell apart due to UV influence, and some old roofing plates - I will fully utilize the old roofing and ditch the foil in the future.
The stack pictured currently holds 6 cubic meters of firewood logs, which is about 9 cubic meters of bucked and split firewood.
As one can see this stack can easily hold a little bit more firewood.
I generally like this solution too, and it also is not an eyesore.
Both my solutions are rather permanent!
My "box" is placed in the corner on one side of my back yard, and my stack is on it's opposite side also fairly cornered.
Both are out of the way and don't interfere with annual back yard work.