Hello DJ,
There have been several debates over the years on this an other forums about nose weight.
The issue is that nose weight has both safety and legal implications, but it isn't always obvious how to measure it properly.
Others may disagree in detail, but you only need to carry as much nose weight as needed to keep your outfit stable. There is no magic number or formula to tell you what the weight should be. So to some extent it is trial and error, but its better to have more than necessary BUT NEVER exceed the limits set by your particular car or trailer manufacturer.
What isn't always obvious is that the actual nose weight a trailer produces is affected by how high the the hitch is from the ground, so the height at which its measured is important. The EU specify the nose weight must be measured with the trailers tow hitch at the same height as when it is coupled to the tow vehicle, and this is where all the current "nose weight gauges fail, as none of them allow you to adjust their length to match your specific outfit.
Secondly Many of the retail models are far from accurate, easy to read or give consistently repeatable results.
So using retail models measure using the wrong methods and are inaccurate - what chance do you have!
Pull the loaded car and caravan onto some level ground. Measure the actual height of the hitch above the ground, Uncouple the caravan, chock the wheels, and then support the hitch on the weighing device at the height you have measured and check the weight.
Both RogerL and Steve77 have suggested bathroom scales. These are also uncalibrated but are likely to be more accurate than spring noseweight gauges, however using a broomstick cut to length is one way, but there are safety concerns if the hitch falls off the stick, how ever there is an alternative safer method which is to raise the scales to the desired height (perhaps use the caravan step and some telephone directories) and rest the hitch directly on the scales.