Emergency Z Endstop for Hypercube 300

The BLTouch in my Hypercube 300 is acting up. :-( I was able to get it running enough to print this by homing the printer on X and Y, centering the carriage, rolling the bed up until a piece of paper between the bed and nozzle started to drag, and then sent G92 Z0 to tell the printer its current Z position is home. I then spent maybe a half-hour in OpenSCAD knocking this design together, which clamps to the right front Z-axis rod and holds an optical endstop in just the right position to be interrupted by a black M3x25 screw in an unused hole in the carriage. Edit the start gcode in your slicer to not home the printer and disable bed leveling...just warm up, purge the printhead, and begin printing.

Once that's done, attach the endstop, loosely bolt the bracket to the rod, thread a screw up through the empty frame hole, and adjust the bracket position so the screw can interrupt the endstop. Unplug your BLTouch (or whatever other bed sensor isn't working for you), plug this in, and