Changing final build plate position
I believe I would want to do:

 M104 S0 ;extruder heater off 
 G91 ;relative positioning
 G1 E-1 F300  ;retract the filament a bit before lifting the nozzle, to release some of the pressure
 G1 Z+0.5 E-5 X-20 Y-20 F{speed_travel} ;move Z up a bit and retract filament even more
 G90 ;absolute positioning
 G0 X0 Y200 ; move to back-left corner
 M84 ;steppers off


Here, Y200 is the depth of my build plate.

This works, but the movement is very slow.