Forgive me for not looking at all the pictures of the Marx transformer you have. It turns out that your transformer has an extra set of terminals marked "TO ACCES. 13 VOLTS".

This set of terminals is used to power your switches. The bottom terminal goes to the track outside rails, and the top terminal goes to the constant voltage plug on the side of the switches. You will have 2 wires connected to this top terminal, one for each switch.


This transformer is not marked which terminals are power and which terminals are neutral (ground).
We will presume the top terminals are the power, and the bottom terminals are the grounds.

You will have the 2 bottom wires hooked up to the outside rails of the track.
One top wire (from the left terminal set) gets connected to the track center rail.
The other wires (from the right terminal set) get connected to the constant voltage plugs of the switches.

Now the switches will be powered independently of the track. The track power could be off, and the switches will still be powered.

Larry