OK, you have my attention. My limited research to date indicates that additional length comes at 100#/ft in an aluminum skinned steel trailer. So 400# for 20 to 24 feet . All that I have read indicates that you want 10-15% of gross trailer weight on the tongue. The same balance on a 20 or 24 ft trailer would result in the car being a little more forward of the axles in the 24 to restore the 15% but you have a longer "tonguebase" (sorry), maybe 2-3 feet. 20 ', 12.5 + 5',17.5' ; 24' , 15 +5' ,20'. My current thoughts are that longer tonguebase (sorry again) is more stable but an extended tongue is a lighter way to achieve that .
I also understand that, in addition to balance, polar moment, weight distributed farther from the center of gravity, has a significant impact. The demo shows a model with the mass at opposite ends of the trailer. See the high velocity that the aft mass achieves. If both weights were moved toward the axle but maintaining the same balance, the velocity of the aft mass would decrease.
There are what appear to be clever electronic stability devices available. I know nothing about them other than what is on the links below. Seem to be inexpensive insurance.
As always, poke at my logic or lack of it!
Mike
www.etrailer.com/Weight-Distribution/Tuson-RV-Brakes/335TSC-1000.html
www.etrailer.com/Weight-Distribution/Hayes/HA81775.html
I also understand that, in addition to balance, polar moment, weight distributed farther from the center of gravity, has a significant impact. The demo shows a model with the mass at opposite ends of the trailer. See the high velocity that the aft mass achieves. If both weights were moved toward the axle but maintaining the same balance, the velocity of the aft mass would decrease.
There are what appear to be clever electronic stability devices available. I know nothing about them other than what is on the links below. Seem to be inexpensive insurance.
As always, poke at my logic or lack of it!
Mike
www.etrailer.com/Weight-Distribution/Tuson-RV-Brakes/335TSC-1000.html
www.etrailer.com/Weight-Distribution/Hayes/HA81775.html