Might I suggest you look at this thread:
https://ogrforum.ogaugerr.com/...lay-not-with-an-itad
It focuses on using relays with insulated track sections to control signals and also provides specifications to purchase the selected type of relay you desire. HOWEVER, after re-reading your first post, I don't know how well that info will work with FasTrack. It should work the same way, but I'm no expert when it comes to FasTrack.
Chuck