You mush have brakes when trailer and load are 750kg as a general guide here, there is multiple categories and braking systems.
My 2t Land Rover can tow 7700 lbs legally, but with brakes and breakaway braking systems, but that is the manufacturers limit, each vehicle is different.
I know you can do it, I had a 4wd truck that was rated for only 1500kg, but it would have towed 3.5t too, but we have to go by manufacturers rating.
The thing is, just because something is legal does not mean it is a good idea & I know how you guys drive there, your highways are much faster than ours
Anyway, I prefer when the load does not exceed the tow vehicle weight with this kind of setup, as when something unexpected happens it can more easily push the tow vehicle around, you may do many thousands of miles with no drama, then this one time....
I nearly lost control of a very small trailer recently with near no weight in it, tyre blew out, it then rubbed on guard and somehow got caught up, it then ripped the axle and collapsed the supports, etc etc, it was a wild scary ride and thankfully it did not come apart and head across the traffic, nor enough to make the tow vehicle lose grip, it was prob 400 or so lbs, imagine the mess if it was 4000.
Don't underestimate what can happen and how quick it can happen, some combos are more stable than others, some are on the brink and just need certain event/s to uncover how close to the edge they actually always were.