As others have stated I think the major issue with the Himi is the screen height with a small contribution from the mirrors.
I have played almost exactly this game before with a DL1000. I do not think the mirrors on the Himi are as much of an issue as on a DL.
I have the standard windscreen in the rear position.
I am 172cm (5ft 8inch) with a Klim Krios helmet. The helmet is fine, not the quietest but not the loudest I have used.
I am also using Double Take Adventure mirrors. I feel the mirrors have not made a difference to the noise but now I can now see what is behind me.
The height of the screen is the major issue for me.
At 80kph (50mph) the noise arrives. The turbulence is not as bad as a DL but the noise is similar.
As I am still running it in I have not taken it over 90kph (56mph).
So like the DL, the screen needs to be either higher or lower.
I have chosen to go lower and am currently waiting for a
Powerbronze short fairing in a light tint. This screen is 95mm (4inches) lower than standard.
This should give protection to the instruments and GPS while allowing a more neutral airflow onto my chest and helmet.
With a 125kph (78mph) max speed wind protection is not really required and some have chosen to take the fairing off completely.
Regardless of the helmet I have always used ear plugs on trips.
I find that the reduction in high frequency sound reduces fatigue.
I do not use them around town.
General comment;
Wind in itself does not generate (much) noise. Turbulence generates noise.
Clear airflow onto your helmet will generate low level noise but rolling airflow off the top of a screen edge will be much louder.
The issue is the height (and shape) of the top edge relative to your helmet.
Design and construction of the helmet also contributes but to a lessor extent.
Powerbronze
short screen pics on Advrider