[Aerkuld]

Before I start, I already know how to measure the actual tongue weight of a trailer, but I have a different problem & I'm hoping someone here might be able to make some suggestions.

I'm trying to establish a method to determine the tongue weight capacity for a towing vehicle. While this would normally be a function of rear axle load capacity, this particular vehicle has a high rear weight bias - much like a 911. Because of this I am certain that the front wheels will leave the ground before the rear axle reaches maximum load. The hitch point is already established, so moving it forward is out of the question. So what would be the basis to determine how much vertical load the hitch can take?
I am thinking that a I am going to have to work along the lines of a % reduction in front axle load, but does anyone have any better suggestions?