The weights allowed for towing are determined by two influences.
1, The maximum allowed by the car manufacturer.
2, The maximum allowed by the Caravan manufacturer.
Most Al-Ko chassis are limited to 100KG MAXIMUM weight on the towhitch.
A lot of cars have low towball weights allowed, some as low as 65Kg.
Irrespective of ANY other weights, you MUST only load to the LOWER of the two limits set as above.
Your car will have its towball weight in the handbook, which is usually very different to the max towing limit of the vehicle, for example the car may be able to tow a load of 3500KG but have a towball limit of 100KG.
The caravan hitch limit for the van will be in its paperwork, or ask the van maker for their limit on your van if you do not have any van paperwork.