I'll omit all the legal and insurance considarations, because they are country specific anyways.
Most Japanese and US manufacturers have limited the weight of an unbraked trailer (class O1) to 450 kg no matter what the size of the car is. European manufacturers have in many models had rule of thumb about half of the empty weight. And what I'm trying to say is that 450 kg limit is not technical or safety limit, it's tradition.
Secondly, when driving and turning, there is no difference if the trailer has brakes or not. It matters only when braking.
In Finland we use unbraked trailers a lot, and the speed limit with those is 100 km/h. And I can assure that the weights are frequently exceeding the limit of the car manufacturer, often even the maximum of the O1 class, which is 750 kg. Very seldom are there any accidents because of overloading.
Mostly the accidents with light trailers are because of incorrect loading i.e. negative tongue weight.
Well, actually the most common accident type with small trailers is hitting the rear corner of your own car or bending the towing beam of the trailer, because you start reversing and don't remember you have a trailer connected.
I am defenitely not suggesting or encouraging to exceed the allowed weights and I'm myself trying to obey those, but I'm saying it's not so critical.
This load is just within 450 kg.
