How to forward the body diode of the mosfet without triggering the parasitic bjt?
To inject current into the body, but avoid run-away currents, the 3_D (3 dimensional) structure must be designed to provide a bipolar current gain less than ONE. That can be done.

In the inherited layout/design I hardened against high-slew-rate transients, the cure was to greatly expand the connections to the bulk, whether the wells or the substrate. 

Insights came after many hours of staring at thermal-emissions (recombination photon emisisons) microscope images.