Well as you can tell, many people do many things to play with the TT and TV numbers, but the fact remains that they are not you.
The issue is simple, you have a TV and it has a max cargo rating. When you subtract your family and stuff you carry in the TV from the max cargo, you have the available tongue weight.
Since your tongue is about 12% of the TT weight, manipulating the amount of water, propane, groceries and etc. may save a few hundred pounds of TT weight but it translated less than 100 pounds of tongue weight.
You can also rest assured that given the available space you will eventually fill it. TV, TT floor plan and TT cost, all have to match; there is not too many ways to get around them.
We pull a 25 ft. TT with an F-150 e-boost TV. When loaded for a long trip, we pretty much reach the TV max cargo limit. The TV does what it was designed to do. More TT for us would mean a bigger TV.