Greetings , hope I am in the right forum.
I try to locate information about obtaining/buying ,installing and using(legal) the US type of trailer hook , on Defender and others here in Europe (EU UK ect).
I am talking about this square tube most US vehicles are using to pull a trailer. The advance I see , is that this can also accommodate other tools , such as a winch , or other "hook" systems other than the European iso ball.
I have on my Defender the original tow "rack" easy to remove the ball , and easy to weld up a winch plate to go instead of the ball. However this rack is a plow, and I find the US style square tube receiver a much more low profile and non interfering when off roading.
A few weeks ago I meat a German registered Uaz van with an US receiver (perhaps it was a Russian receiver) , but I never got around to the information I am looking for now.

I have both a drop-style tow ball and a 2” hitch on my OneTen. To be honest I have only ever used the tow ball for towing, the 2” receiver gets used for a mobile workbench. I think the position of the receiver hitch may be higher than recommended for most trailers and I’m still not entirely clear if they are legal to use for on-road towing in the UK.
Here is some information on them (I get an expired certificate warning when opening the website, but it’s all good) https://ntta.co.uk/law/towbars/type-approval
This information is not specific for a Defender, but it should be noted that Light Commercial Vehicles do not require a European Type-Approved tow hitch. There is a good chance your Defender is classed as an LCV and so will be exempt from type-approval - check your v5!