So if the instability comes from the trailer bouncing being able to unload the rear tires then why should it matter if the weight loading the rear tires comes from tongue weight or from 2000 lbs of weight in the bed.
I guess I should have phrased the question differently. I guess I should have said can anyone explain the physics involved in why tongue weight is important. I know the conventional wisdom is that more tongue weight within reason makes it more stable. But there are other variables involved not just tongue weight. A short dump trailer will be stable with much less tongue weight percentage wise than a travel trailer. I would guess that length, how far away from the axles the weight is and even the frontal area of the trailer and how fast you are going all play into it. The wind pressure on the front of the trailer should actually have some ability to push back and rock the trailer back reducing tongue weight. The weight distributing hitch bars also transfer tongue weight back to the trailer. They can also be used to transfer weight to the front axle over and above what the tongue weight is. So even if the weight was in the bed the WD hitch can still transfer some of that bed weight to the front axles.
