Layer 6 problem

[Psychotronic]

Not really. It should still look like a solid wall until Jack tries to jump through it, and then he'll walk right in front of them, which looks very much like a secret pathway. I think there's even a couple of secrets like that in the original eight mansions. But if you want him to go behind the wall instead, you can always put some fringe-less bricks in layer 6 instead of layer 0. Then Jack will pass in front of the fringe and behind the bricks. It'll look a little weird, but it will definitely look like a secret.