In that case, just declare the array to be of type :object and cast it back when you use it.
But it will none the less still need 2000x2000x200 + 2000x2000x4 bytes (first for the actual objects to fill the array and the later for the array) so you can only lose there.
ps: on the 12 bytes. I assume thats because globals need to be present anywhere and thus their RAM block is allocated even when not needed to make sure that there is place for this global when a local variable is assigned to it.
But it will none the less still need 2000x2000x200 + 2000x2000x4 bytes (first for the actual objects to fill the array and the later for the array) so you can only lose there.
ps: on the 12 bytes. I assume thats because globals need to be present anywhere and thus their RAM block is allocated even when not needed to make sure that there is place for this global when a local variable is assigned to it.