I like things to be solid so I combined the E3D and bltouch mounts together. There is no flex at all. Marlin settings are:

X_PROBE_OFFSET_FROM_EXTRUDER 30 // X offset: -left +right [of the nozzle] Y_PROBE_OFFSET_FROM_EXTRUDER 15 // Y offset: -front +behind [the nozzle] Z_PROBE_OFFSET_FROM_EXTRUDER 1 // Z offset: -below +above [the nozzle]

I also had to configure Z offset which is 2.5mm.

Recently I added a drag chain so I modified the E3D mount to include an adapter for drag chain on top. Works very well.