automatic reversing loop mechanism

Hard to say, the picture has something going on that won't let me right click on it.
Looks like the loop at wind river may be where it's needed.
Is this DC or DCC?
Left side of pic at the 10ft mark, the three tracks that run thru there should be cut and everything below the 10ft mark should be on the reverser.
I have used the Digitrax PM42 with a Zephyr. It will need to be adjusted through the LocoNet to work with the Zephyr, see the tech notes on DigiTrax web site.
What I don't like about the PM42 is the use of relays to switch the track polarity. They go click-click.

Tam Valley's Frog Juicer can do reversing and there are a couple of others that sell relay-less reverser modules.