So I spent the last 2 nights learning XTrkCAD, and set up the layout. And running the trains alerted me to quite the problem. The spurs making up the yard only have the track leading back to the turntable for switching out, and limits the length by a bit.
So now I'm fiddling with it and trying to see if I can't move anything around and get more space out of what I've got. And to clarify, I'm leaving it all flat, now, no grads at all. Too much of a headache.