Covering round bales

It’s probably been cussed and discussed before but just wondering. I’m wanting to use an old trench silo to store round bales in. It’s 120’ long, 15’ wide, side walls start at 4’ high, in the back it’s 15’ high. Sides and back end are completely vertical. Concrete walls and floor. Wondering if I could stack the bales (5’x5’) 3 wide on bottom, 3 wide above that, then 2 wide on top, and then cover it with silo plastic. What would be wrong with that? I could just drape the ends or completely seal it. Or am I just going to have to use several tarps? (And why?)

Covering round bales