I have a Lance 1685, gross weight is 5400lbs. My tongue weight is between 600-750 dependent of what and how I load it. Trailer generally comes in at 4500-5000lbs.
The van with a 3.5/3:73 is rated for 9000 GVWR, 12,600 GCWR and 7200 lb.towing capacity, (according to the brochure from Ford).
The factory supplied hitch states max. tongue weight non WDH 500lbs. with WDH 770lbs.
Then Ford go on to say they do not recommend the use of a WDH...maybe because there is no chassis, just unibody construction.
I am going with a class 4 hitch (800/8000lbs non WDH and 1000/10,000WDH so I'm not so close to the limits of the factory hitch.
When the weather clears up around here, maybe this weekend, I'll drop the trailer on the van and see how things look. If I can get away without using the WDH, great...we'll see how it goes.
Cheers, Dave.
EDIT...I just found another site that states my towing capacity with my van's configuration is 6800lbs. So I wonder which is correct, or split the difference? Either way, I should be good to go.