Hi,
Thinking back to the old Cathode ray oscilloscope days, I remembered that mu-metal was used to shield the 'scope from the transformer, viz:
https://en.wikipedia.org/wiki/Mu-metalAlso, as you know from other forum threads, I'm using a compass/gyroscope board as part of the Voice Controlled Edwardian Steam Launch navigation system. I've positioned the compass up in the roof of the launch, as far as I can get from the steam engine and electric motors. I've used it successfully for compass control of the rudder, though I haven't carried out any "scientific" calibration of the system.
Perhaps you could carry out a similar exercise they did in the War, when calibrating the HUF-DUF radio direction finders, and actually make a "calibration compass map" by turning the boat through 360 and prompting the computer with the exact direction and build a look-up table ;- depends if you want the ultimate accuracy.
I like your YouTube video of the system in operation, very advanced I must say. Will you be displaying data in graph (parameter v. time) form; I would find that very useful for monitoring my boiler controls, i.e. pressures and temperatures.
Ian.