Hi Richard,
The caravan manufacturers do not post actual nose-weights - probably for the simple reason that they don't know how you are going to load the van.
Rather, they have listed the maximum design nose-weight for the caravan A-frame, which at 100 kg is also the limit for the AL-KO coupling heads.
Likewise the car tow-bar weight you mention is also a maximum, and the legal maximum nose-weight is the lowest of the three values. In your case 85kg.
So you need to load the caravan so that you don't exceed the 85 kg limit
Robert