Yes, what you say is true, but a simple formula could not take into account every possibility (as you describe and/or turning in a corner, for example). What I'm talking about would merely be a formula based on a level surface and only a change in the position of the front wheel of the TV being considered. While it would not replicate the real-world, it would give us a consistent, baseline number to have in mind when adjusting the pin and hitch AND it would give greater credibility to the whole notion of using a 6 inch gap as a target number, as opposed to 5 inches or 7 inches. I suppose another formula to consider would be a worst-case scenario in which, on a level surface, the trailer axle (assume a single axle) dropped as much as, and at the same time as, the front axle of the TV , how much drop would be required to make contact at the tail gate with a 4, 5, 6, 7, 8 inch gap? I assume then that the distance from the hitch (or TV rear axle) to the trailer axle and also the hitch (or TV rear axle) to the tailgate would have to be factors in the equation. Now that I've said much more than I know :) .....hope there is a great math mind in the group who can help!
HD
(BTW, both the academic and the skeptic in me comes out when "they" make some recommendation that could easily be quantified but has not been. "They" say to replace your mattress every 8 years. "They" say replace your MC helmet every 3 to 5 years. I have not seen any independent, scientific study to support either of those recommendations.)
Thanks again, Troubledwaters. Hope you are having a good day in your part of the world. Mid 80's for high here in Central Texas today, so we are enjoying the weather more than usual.