You are not doing anything to defraud anyone. If you went to a local welding shop and had the metal part replaced, what would they do? They would remove the tag and place it on the new part. Swap the tag and be finished with it. I did not know HF used a tag that was removable. The vin number on most trailers (four of mine) is stamped into one of the front braces; another has no vin as it was registered as a home made back in the '70's.
I like the idea of adding the center tube. Let it go back to first cross member; but the hitch does not need to extend more than a foot in front of the angled braces.