I'd suggest confirming that in writing with them!
FYI - Relevant section from the AAMI PDS below. Seems pretty clear after another read though so I'm satisfied is alleviates my main concern which is damage to other persons property etc.
Third party property damage for caravans and trailersWe coverWhen your car is towing a caravan or trailer in the period of insurance and loss or damage is caused to another person’s vehicle or property as a result of:
• the actions of your caravan or trailer;
• your caravan or trailer running out of control after separating from your car while your car is
moving;
• another vehicle colliding with or trying to avoid colliding with:
– property falling from your caravan or trailer while it is being towed by your car;
– property being loaded or unloaded from your caravan or trailer attached to your car;
then we cover the amount you are legally liable to pay another person to compensate them for loss or damage to their vehicle or property.
Limit
The most we will pay for all claims arising from any one incident is $20 million including associated legal costs we have agreed to pay.
Note: If you claim under this cover, you cannot claim under Third party property damage for the same incident.
We do not cover• damage to the caravan or trailer being towed;
• damage to the actual property that falls or is being loaded or unloaded from your caravan or
trailer.