Weight Distributing Hitch advice?

2013 Tacoma with factory tow package. With a travel trailer that weighs more than the truck, say 6000 pounds, there is choices in hitch capacity. Most seem to say that having a hitch with 750 tongue capacity would be fine, but my question is: With the trailer heavier than the truck, should the capacity go up to 800, or would it handle better by going down to 600?

Should it move stiffer or softer when the tail wags the dog, so to speak?

 

Tongue weight should be no more than 650lbs according to the owners manual. Tongue weight is not a measurement of the physical capacity of the ball mount itself; it is the downward pressure placed on the ball by the coupler.

The distribution of the weight on the trailer determines how much tongue weight is placed on the ball mount hitch.

See this for info: http://www.etrailer.com/faq-trailertowtips.aspx and http://www.etrailer.com/faq-weightdistribution.aspx