The best information (IMO) to clarify the "status" of a trailer's originality can be found here: Price vs Condition
. It's an awesome tool for both buying and selling and analyzing what you have or are looking for.
But basically, a selling owner can "call it" whatever they want and the buying owner "can do" whatever they want to. It is a good idea though to study all the pros & cons to the decisions you make along that way during your restoration/remodel.
Good luck with your search!