There are two reasons why the Alko jockey wheel with the "nose load" gauge fitted is not great. Both reasons have the same problem.
The nose load is created by moving the load within a trailer sothe trailers centre of mass is just forward of the trailers main axle. This produces a torque around the caravans axle that forces the nose downwards. Torque is measured in Newton metre's (Nm) Which is force times radial distance about a turning point, but rather than converting to NM most peopel use a simple Kg value.
In this case the the turning point is the caravans wheel axle, and the distance is between the hitch and the axle. Assuming nothing you do nothing to change the load inside the trailer the torque about the axle is the same, but it you support the trailers "A" frame anywhere other than the hitch the distance to the axle will be shorter, and that means the force or load (Newtons or Kg) will increase proportionately as the distance decreases.
The Jockey wheel is always closer to the axle than the hitch is, so consequently the measured load will be greater than at the hitch. The second problem with the Alko JW design is the actual load measuring device is fitted to the JW's axle, which is not concentric with the JW's post, and it can swing 360degress which means depending on which way the JW wheel points will also change its distance from the trailers main axle, and thus should change the value it will display.
These difference may not be much, but they are never-the-less differences, which the user should be aware of and to understand they will give an artificially high reading compared to the true noseload value.
The Nose load you need is not a precise value that you can predict with any great accuracy. That is one reason why the UK Caravan Industry recommends trying to achieve a nose load of between 5 and 7% of the caravans MTPLM.
Often that is impractical for some outfits becasue the tow vehicles nose load limit (the "S" value) is less than 7% of the trailers MTPLM, and many caravanners have no problems running nearer the 5%.
I personally used to aim for 80 to 85% of my cars "S" value and was always satisfactory for me, but others might find they need to go closer to the "S" value limit.
In practice there are far cheaper ways to measure and control nose loads as I have previously suggested.