Fly to areas where NPCs attempt to scan your cargo (only lawfuls will announce it before scan)
NPCs try to approach but cannot get in range, because collision prevention prevents them from going that close. Only way to complete the scan is if the pilot of the large ship reverses or strafes directly iunto the stalking patrol.
this also means such large ships are immune to NPC cargo scanning in some situations, which might not be intended...
Maybe this could be fixed by giving NPCs scanners with slightly longer range?