Trouble getting dual Z end stops + steppers to work (no replies)

I'm trying to enable dual Z endstops on my Folger Tech FT-5 printer. It's a cartesian setup with two Z steppers on opposite sides of the build platform that raise/lower the bed in tandem.

The dual stepper feature works, but my 2nd z endstop doesn't seem to do anything.

What I'm trying to do is have each z stepper home independently to compensate for either of them getting a bit higher/lower than the other.

This is what I've done so far.

I've commented out:

#define Z_DUAL_STEPPER_DRIVERS
#define Z_DUAL_ENDSTOPS

and have enabled:

#define USE_XMAX_PLUG

since I see:

#define Z2_USE_ENDSTOP _XMAX_

I'm running Marlin 1.1.0-RC6.

I may just have my head wrapped around this incorrectly.

M119 shows:

SENT: M119
READ: Reporting endstop status
READ: x_min: TRIGGERED
SENT: M105
READ: x_max: open
READ: y_min: TRIGGERED
READ: z_min: open
READ: z2_max: open
READ: ok

That makes sense as I have:

const bool X_MAX_ENDSTOP_INVERTING = true;

But I think what I really want to see is z2_min or something like that. Any advice on how to get this working appreciated.