The reason I like your idea is because you will get tremendous heat build up in that shipping container.
This is my non-ventilated wood shed. That's right, I even plugged the ridge vent up top with fiberglass. I keep the door shut.
I am getting hickory down to 17 percent moisture in 8 months.
Now, this structure is entirely wood, and the floor is 16 inches above the ground. Massive roof overhang.
Rain rarely hits it but it gets lots of sunshine. Water vapor passes through the walls and floor.
I live near the French Broad River and every other night, my place is enclosed by river fog. It rains a lot here. My firewood misses out on the moisture from rain or river fog.
It heats up but not as much as I had hoped. On a sunny day I pick up about 8 degrees. So if it is 90 degrees, I get 98 in the wood shed. I had hoped I would get more heat than that, but, I am very happy with the performance. This shed is 4 years old.
Of course if it didn't work, pretty easy to add some windows or even fans. But no, this Bad Boy doesn't need ventilation.
Even when I have just loaded it up with green wood, it still remains dry, no hint of mold or mildew. Plus bugs and rats don't like 98 degrees either.
So, your shipping container is going to pick up some serious solar heat and I bet you get 20 degrees above outside temp on a sunny day. Of course you have to have ventilation. But like I said I would like to see you try 2 sq. ft on the bottom of one end, and 2 sq. ft. on the top at the other end. Minimize ventilation, in order to maximize heat.
Or, if you had no ventilation and just a big door, leave that damn door closed on a 90 degree day. At 4 pm open that door and check your interior thermometer, I bet you would see 110 in there and maybe 120. The thing is that, by 4 pm all the wood would be up at 120.
Water vapor is going to be checking out of 120 degree wood.
Just leave that door open for the next 4 hours, what a massive release of very humid air.