You can level with 4 z motors and a probe using this method on RRF2.
https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors
You need to add a command to config.g that defines where the lead screws are physically located in absolute coordinates relative to the 0,0 point.
You need to create a bed.g file that has 4 points to probe as close to the lead screws as possible.
Details in the link.