Hi, all'
As a retired Firefighter with 26 years experience, I never tow with Car and caravan locked together. My latest 'Van has the 2004 stabalizer and I have the Safety Hitchlock supplied by Alko, which they say is o.k. to use whilst towing. This is true in the sense that it does not interfere with the overrun Braking or articulation. What it does interfere with, by design is preventing anyone including the owner from disconnecting Car from 'Van in a hurry!! Modern Fire Appliances carry a whole manner of gear, mainly designed for rescueing people from Road Accidents.
However none of this would quickly remove a Hitchlock. I agree that Bolt croppers would cut a chain or padlock but hitchlocks no. Also bear in mind that in an emergency you might want to seperate the unit immediately, before any help had even been mobilised. Consider this, what seems an easy task ie. Unlocking the Hitchlock in the calm controlled environment of Home or a campsite, might take on a completely different aspect if say the caravan was on fire, and clearly, easy disconnection would at least save your Car. Add to this the panic, fumbling for keys, maybe in the dark. Also consider that in the event of injury you may be off to Hospital ( Keys in Pocket) leaving the Emergency services stuck, with Car and 'van. That they can't recover.For me the safest way of using any locking device is to fit when required ie. stops at services or when pitched. Finally I know the above might frighten or give people concern. Statistics show that whilst towing you are at less risk from accident than when solo. Enjoy.
Eddie.