While I'm no electrical wizard, other than your two sidings being cut from layout operating power, I'm not sure why you think you need "blocks?" Seems to me, you could start your star wiring pattern with terminal strip under the layout right next to the transformer / TIU, and then run a series of multiple length wires from that terminal to well spaced locations around the layout where you make track connections. The longest wires would have to make the run all the way from your start location by the yard to the track on the opposite side of your center opening. Do you have, and, have you looked at, Barry's DCS book?
I've also noted a slight operational problem with your track plan. Once a train starts running counter-clockwise on your yellow loop, there is no way to reverse it without traversing the green loop which has 2 reversing loops included. However, if you include another connection from the topside of the yellow loop on the left into your yard area, now your yellow loop will also have 2 (instead of 1) reversing loops, although one will be a little convoluted. This would allow trains to reverse directions on both the yellow and green loops without interfering with each other.