Displacement and weight are two different concepts.
It is not reasonable, not practical to provide a displacement figure for a water ballasted boat with its tank empty. The boat will be unstable and not meant to be used that way. It may be done to further the marketing impression that the boat will be easily trailerable. A more responsible way would be to quote the weight of the dry boat on the trailer and not the displacement. I tend to believe the owners when they indicate the boat's is closer to 2000 lbs. I believe the difference lies in the bouyancy afforded by the empty tank vs the bouyancy lost with the tank full. Everyone seems to agree that the boat with its ballst tank full displaces 3,000 lbs before motor and goodies. So for towing purposes I would take the owners indications of 2,000 lbs plus 1,500 lbs the weight of trailer and another 300-400 lbs of goodies. Your towing weigh will be close to 3,800 lbs. You should take the rig to a weigh station and have it weighed. Not a smart claim by Hunter in its brochure.