Agreed. 12,000 is about what our F550 wreckers weigh, and all the wrecker stuff weighs as much as the trucks we stick them on. Assuming that we're discussing a pickup truck here, you're talking 7000 pounds tops. 12K is a very reasonable GVWR, (gross vehicle plus load) which you'll find on the door jamb sticker.
An empty one ton pickup will move a deuce with a stiff hitch. It will not do it well, and if/when the front wheels flip (search the archives about this, when/where/how common it is), you will not simply destroy the tires on the towed vehicle, the towed vehicle will follow it's own wheels and take you with it.
If you've got a properly sized wagon (not much room for overkill, and obviously underkill is no good), you can set that up on a gooseneck/fifth wheel arrangement without leaving any comfort zones, but you'll want to be on top of your registered weights and all that, and you'll be balancing it pretty careful to get the weight where it needs to be.
