NO you CAN'T!! If your so sure your right despite all the evidence to the contrary Perhaps you can produce some proof???
The link you referred to says nothing about MAM of a trailer needing to be under the vehicle's towing capacity, for B+E. I suggest you read the regulations properly, rather than skim through them (you quoted a standardised licence restriction for C1+E) then you'll see that those regulations don't apply in this specific case.
It is a principle of UK law that you can do something, until a law says you can't. There is no law which says you can't tow a trailer with MAM exceeding the vehicle towing capacity, so long as its not loaded beyond the vehicle towing capacity.
The devil is in the details of the wording of the law - you're jumping to assumptions, and many other so called official bodies, etc have also misinterpreted the complex regulations too, so I'm not surprised there's a lack of acceptance on this issue.