Dave, if you're NOT planning on, or already, using one of the outside insulated common rails for block signal system, there is an easier way to wire up the mechanical brass crossing gate and the Crossing buck lights.
Essentially if you can dedicate an insulated common rail section for the crossing signal operation, then the DZ1070 infra-red detector and the DZ1008 Relay can be taken out, and replaced with a simple DPDT 12 VDC relay, maybe even SPDT. Just need the train wheels and axles to complete the common feed to the 12 VDC DPDT relay coil, and then use the relay common (wiper), and NO contact to switch +12VDC to the rest of the circuit as drawn.
I am working on a schematic to see if I can do this on my layout without impacting the signal system. It's kind of a "block within an existing block" that will drive the crossing gate, but not alter the signal system operation. I am sure it's possible, I just have to play with it and set up a test section of track to verify that it can be done. I don't really care for having to use the DZ1070 and the DZ1008, they're pricey and they only work in one direction...