Andy, I built a frame around the bottom side of the HCD out of 2x2, so the layout wouldn't be resting on the wiring if I wire it under the deck. I also have a couple of boxes of plastic cable clamps that I'm using to secure wiring to the underside. Even with that soft, compressed paper (beaver board) cladding of the HCD, a decent little construction screw holds them pretty securely. I built the interior spurs just as shown, but the three-branch spur at the top, and in particular that branch that has the s-curve in it, will be used primarily by my switcher except when I have a train pulling into the station. And then, on the other interior spur, it's a straight shot into what will be the two-door engine house. I really like your idea of putting the foam panel on a framework on top of the door, creating a semi-open space between the foam and the door. I had no idea that was a 'traditional' method, but I do recall seeing many layouts built that way that weren't on a door. It just never occurred to me to incorporate that idea into my HCD benchwork. My foam isn't permanently attached to the HCD, so I could (theoretically) slide if off of the door and construct that frame... which is exactly what I think I'm going to do. I might use 1x4 (or 2x4... but that's going to add a lot of weight) instead of 2x2 though, so I have space enough to more easily reach into the cavity between the two. That may not be a 'solid, best answer', but it'll do brother... it'll do! Thanks!