You need a proper NATO hitch, the LR ones are rated to 4.07 tonnes.
as was said, for a sankey trailer (I use the name "sankey" as a generic thing, but they've been made by several different companies over the years) with a FIXED eye, you need the rotating ability of the NATO hitch.
Some earlier trailers had a movable eye, in which case you need to LOCK the hitch, otherwise the eye & hitch combination can rotate 90 degrees, then you won't be able to turn left or right without some major damage!
The hitches are here on ebay very oftem, usually go for about £30~£40 for a decent one. you can buy all the spare parts from Dixon Bate to totally rebuild them, i've done several over the years, they come up really nice when they've been shotblasted and painted, with nice shiney new clips etc.