Originally Posted by lnussbau

I just got back from the Jubilee in Branson, where the TM founder's son Mike spoke in a "tech talk" session. He suggested that the max for a WDH on a single axle TM is about 750 lbs. The reasoning was (partially) that the very sudden weight transfers during a "porpoising" session can overwhelm the tires, especially the 14" ones. Think of 500 lbs or more suddenly appearing, then disappearing, on the axle/tires -- repeatedly.

Still, many factors will determine what you need. One item that has occurred to me is that pickups, unlike some other vehicles, are engineered to run both with and without a load in the rear (up to a point, of course). Just food for thought, to add in to all the other items people have discussed here.