I finally had both the time and opportunity to weigh the boat on a scale I feel was accurate. A nearby grain elevator has a drive on scale used for weighing trucks and trailers bringing in their harvest. The scale's digital readout is active 24/7 and the owners don't mind locals using it on off hours. So one quiet Sunday afternoon I decided to put it to use.
I came to the conclusion with a little work the process could yield several different weights that could be helpful. So I planned to take four readings and here are the results -
Note - Onboard was 40 gallon of water (320 lb) and 8 gallon of gasoline (48 lb) = 368 pounds
Then the math -
The important numbers -
Empty Boat weight - 6252 lb
Empty Tow weight - 7972 lb
Empty Tongue weight - 560 lb
It should be noted the weight has the potential to be increased by 1120 lb if both 80 gallon of fuel and 80 gallon of water are loaded. My 09 Ford truck's rated towing weight is 9800 lb so even with additional gear onboard I should be within its capacity. Normally though I am loaded at less half capacity of fuel & water so I am well under the rated weight.
Also, because the fuel and water tanks are situated forward of the trailer's axles the tongue weight will also increase somewhat as fuel and water are added.
* I unloaded the boat and drove back to the scale with the empty trailer