trailer tongue weight

[bumpdraft]

Getting ready to do a restore on my old trailer for my 23 cc. I never actually weighed the tongue, but it has been like it is with the boat in the same location for many years. I got to thinking about the possibility of moving the axles to the rear a couple of inches.
I didn't want to go to the scales , fight the traffic and so forth, so I was looking for a different method of weighing, using a bathroom scale. Using a piece of square tubing, some bricks, a few lengths of pipe and the scale, I positioned the trailer between the scale and a point on the brick on the other side, exactly one foot from trailer to brick and two feet from the point on the scale. (hope this makes sense)
I got a reading on the scale of 120 lbs. and since the two outward pipes were three feet apart, the tongue weight would be 360 lbs., which is about what I would have thought it to be. The fuel tank is almost empty right now, so with gas, I would expect to be a little more weight on the tongue.
Just wondering if anybody here has done this and later confirmed with a proper scale.