Hello Surfer,
I'm not sure why you think that VOSA and the other authorities are not bound by the Directives and regulations. Granted they are quite complex, and you have to have your wits about you to sometimes see the methods and logic, but they generally are logical, and that can become clearer if you stop and think about what is actually happening when you couple a trailer to a tug.
I have recently made a mistake regarding the interpretation of Gross weight and towed weight, - probably a senior moment, but the regulations and directives are quite specific, and you do need to know the differences between what appear to be quite similar terms.
Lutz has been very consistent with his interpretation on the matter of nose loads, and it does make logical sense, which in this case may seem to counter intuitive.
Fortunately, if you choose to disbelieve the directive, then if you stick to a caravan with an MTPLM that does not exceed the cars max towed weight, then you are within the limit by the value of the nose weight - no harm done.