I have stacked next year's wood between all my close trees, then moved on to stacking on pallets (3). Lack of flat ground required me to shim a couple corners of the pallets with bricks and wood blocks to get them level. Now I have more wood to stack and will be using pallets, but I don't have any convenient, flat ground left. I'll probably have to shim with some cinderblocks or sacrifice a few splits. Anybody had to shim like this and have any guidance or gotchas I should look out for? Unfortunately my remaining areas will be under trees and not get much sun once the leaves come back out. I plan to stack everything criss-cross to promote air flow since I'll won't have much sun.