Although I think your idea is somewhat intriguing I do want to note that it doesn't have to be 3 blocks wide, I could probably do it with 1 empty space in between (to place redstone dust). Of course I would need some space 'elsewhere' to build myself a small contraption
But on the other hand: I doubt anyone would like to see all those glowing lines running through the walls all of a sudden. So you'd still have to do some hiding of the stuff. And then I no longer see the advantage anymore, at least not in this example.
Doesn't mean I don't like your idea, but I am a bit indifferent to it.
That's what I meant, sorry if it wasn't clear. You have one empty space between the ceiling and the floor, which themselves are one block each, so 3 blocks total.
Also, I was not expecting the blocks to have the signature "redstone dust glow". However, that does bring up an issue, which is that you want the blocks not to show the glow, but at the same time that makes it hard to know which blocks are redstone-wired later on.
I would solve this problem by making it so that when you are holding redstone dust in your hand, it causes the redstone-wired blocks to glow. Otherwise, they look the same as their non-wired versions.