Using GWX 3.0:
I loaded my save after I sunk the ship-CTD.
I loaded a previous save under a different name while I was stalking the convoy and prior to sinking the ship-loaded fine. I saved this one while surfaced, within sight of about a dozen ships, probably within 12km.
Obviously more testing needs to be done. I use the fire damage mod in SH4 and have had no problems but people have had issues with the DC disturbance md in SH4 and I haven't tried that.