Here's the code I used if anyone comes across this post in the future
M584 Y1 U2 P4 ;Separate Y Axis into Y&U and show U axis on UI M564 S0 H0 ;Allow movement without homing as U axis not homed G1 U2 ;Move right hand side of Y axis 2mm from endstop M564 S1 H1 ;Enforce axis minimums and maximums and only allow movement after homing M584 Y1:2 P3 ;Rejoin Y axis and hide U from UI