OK just before I start, I do know what does and doesn't constitute valid housing in Terraria. I'm also playing v1.2.4.1

What I'd like to know is does the "must have a door" requirement also mean "must be accessible", or can I create a walled-off cube with internal doors to satisfy the housing rules? i.e. are any of the houses A, B, C or D in the following diagram valid?

If I can, then I'm going to be making pressure-plate/activator automatic doors that don't get torn down in a blood moon.