They'll just take it by the chains
Only a single chain on the Heaslip and that is padlocked in a tight loop around the OzHitch pin, which is combination locked into the trailer end of the hitch.
Depending on how far We will be from the trailer I also lock the stabiliser legs and / or fit the wheel clamp.
I know that, in the big smoke, trailers are stolen and sold for scrap, but like to think that is a bit more difficult in the bush.
In the end though, as others have said, just so long as it makes the neighbour's an easier target my rig will probably be safe.