I have been looking at some of the Type III 2" hitch motorcycle carriers to carry an Enfield 500 that weighs 350#. Most specify that the tongue weight be capable of the 350# plus the carrier itself, an additional 85#. 

All the information I have found indicate the tongue capacity for a vanagon to be 150#. Is this accurate? Is it possible to carry this 350# bike without using a trailer?

Owen