@ortondale The BLTouch SZP coil at Formnext was a prototype. It's other feature was that its mounting centres matched the BLTouch. I think it hasn't been fully tested to see if any parts of the BLTouch affected the SZP readings. @T3P3Tony would know that, or if there are any of these coils any available.
I don't have the full schematic of the existing coils to know if they could be drilled, apart from the images shown here, which do make it look like there's space: https://docs.duet3d.com/en/Duet3D_hardware/Duet_3_family/Duet_3_Scanning_Z_Probe#coil-dimensions
Though I'm not sure if it would affect the SZP reading, or if I'd be brave enough to drill one out myself!
Ian