I have no idea, of course, what the conversation between your aunt and the trooper was about but perhaps your aunt had her truck registered only for shipping or empty weight. The trooper's warning may have been that she should go in and reregister her truck for its rated weight or GVWR because she was over her registered weight when pulling her trailer. That is what happened with Cumminz who started this thread. She or the DMV clerk may have got it wrong and she bought a commercial license plate instead of an ordinary license plate with a higher registered weight.