I also have a four track yard and am stuck with #4's as a result. We can't change the laws of physics and create space out of thin air. I will say that laying out a yard with #4 switches takes a good bit of care and testing in track laying. If you get everything straight and smooth and get all the points filed so the cars go through the switch smoothly, you can move some pretty good size equipment through a #4 at slow speeds. I have an 80' combine that regularly switches in and out of the yard with no problem as long as I keep the speed down. Now, if you just slapdash your yard together, I can guarantee you that you won't be able to get a 40' boxcar in and out.