If the latent space is meant to be highly spatially correlated, could you simply apply random rotations of rows and columns† to the latent space throughout the process? That way, there wouldn't be specific areas data could be smuggled through.
† As in, move a random vertical stripe of the image from the right to the left, and a random horizontal portion from the top to the bottom. Or, if that introduces unacceptable edge effects, simply slice the space into 4 randomly sized spaces (although that might encourage smuggling in all of the corners at once.)