Hello Robert,
Assuming the nose weight gauge is actually shorter than the vertical height you need to achieve, you need to pack the gauge up until the correct height is made.
If the gauge is too long, then unless you can cut it down, then I'm afraid its not suitable for your purpose.
I have serious reservation about the majority of commercially sold so called nose load gauges;
Most are fixed length and thus probably do not meet the need for the height requirement.
The scale graduations are not really fine enough to resolve to the Kg level,
Most are not calibrated, so their accuracy is doubt.
some that fit to the top of the tow ball raise the hitch and thus will under read the actual nose load value.
Using bathroom scales with pole and load spreader is probably more accurate, and you can actually calibrate the scales fairly easily.