Interesting query....In the U.S. They aren't "approved" per se. I have towed a 22 ft boat (~ 1100Kg) with no problems. Mostly I use the pintle for my M416 trailer that typically maxes out ~450Kg
I seem to recall someone on Mud posting a 2000Kg tow rating from an Aussie owner's manual. I'll see if I can find that posting.
What are your plans?
Dave