I did ask the question that way round just after the new regs came into being, and the reply is what I based my opinion on.
But, I no longer have the email and I have since seen so many conflicting viewpoints that I'm not sure it'd make any difference anyway.
Safe route?
If in any doubt, either confirm with the relevant regulatory body in your location or just get a test anyway...
If the caravan maker has had the chassis made to an agreed spec / design with a Model statement (I think that is the right words) rather than having everyone inspected individually then you could strip it down to that same state as long as what you put on it complies with any guidance in that statement.
However I cant see the caravan makers sharing that document with you & you would need it to show compliance.