Don't forget the legal side to this. What you can legally tow depends upon the numbers stamped on the VIN plate.
There will be 3 or 4 weights in kg. The last two are maximum axle loads, and can be ignored.
The first one is the gross vehicle weight, the second number is the gross train weight. Subtract the second from the first to work out the maximum trailer weight you can tow. If you get into an accident or are pulled by DVSA, and put on a weighbridge, the GTW is the number that they will be interested in.
If the second number is blank or 0kg, then it is likely that the vehicle is not homologated (approved) to tow, and you cannot legally tow anything.