Torque on wheel nuts, any nut for that matter except perhaps for high tension steel, is not confined to a caravan.
For example, if the wheel nuts on your vehicle are the same as the caravan, torque will be the same.
You can Google the size of nut and torque value. Here is a guide:
'The optimum torque value for your car or mounted rims can be found in the vehicle manual. It depends on the car model, rim size, design (aluminium or steel rims) and number of bolts. It is normally between 110 Nm and 120 Nm.'