Locking a trailer to a "swan neck" tow bar

[Origin Unknown]

Can't find the trailer sub-forum so posting here.

Any useful advice on locking a trailer to a swan neck tow bar? Needs to be something that can be used while towing too. This is the trailer and hitch if that's of any use.

[Origin Unknown]

Cheers. I've been doing something similar with the tow bar mounted cycle rack. However, the towing eye screws in so I have to be clever when routing the kryptonite lock cable to stop it just being unscrewed. Surely there must be something that clips over tow bar to stop it being uncoupled?

Second question, the loop at the front that chocks the wheel, anyone know what it's called and where to get one?

[Origin Unknown]

Thanks and Merry Christmas!