Scott,
It never hurts to have power toggles, if for nothing other than trouble shooting electrical issues. If you don't plan to store engines or lighted cars on the spurs, then I don't see a need to toggle those, at least not for DCS. I don't know about TMCC, but assume it's the same.
The width of the yard might have been less because I didn't know how close the switches could be to each other, so I spaced them based on the footprint. However, it looks like the switch footprints are actually smaller than those in RRT.
When it comes to adding a 5th spur, it looks to me like you may have to shorten the other spurs by 1/2 or 1 track each, so you might not gain enough added storage to make it worthwhile. However, if the switches fit next to each other, then it looks like you could gain about 5 tracks worth of storage. If you shorten the lead track, you simply reduce the length of a train that will fit. In the photo I shortened it by half a track. And you might be able to move the escape half a track to the right.
If you swap out the O-27 switch for an O-42 switch, you're going to have to cut an O-42 curve to fit like it shows in the circle.
I knew you hadn't tacked the track down, wired it, etc. Still, you made good headway test fitting everything and getting to this point.
