Any motorcycle engine, run continuously for 30 minutes, reaches a normal operating temperature inside the crankcase regardless of the ambient air temperature. Guaranteed.
I have friends in and around Mandello del Lario and Switzerland. They ride almost year round and quite extensively in the Alps.
To my knowledge, none of them have ever had any issues which would cause them to want to make this major modification to their Stelvios.
I too, don’t want to pee on the parade, but I am grasping at straws here in trying to understand the reasoning for doing this.
With regard to “milkshake” inside the valve covers, it has been my experience that this is caused more by rain, and the sudden rapid cooling of the engine in the presence of moisture saturated air. This becomes especially apparent when people take a hot motorcycle to a self-service car wash, and then blast the engine case with cold high pressure water.
It is my belief that any moisture in the air in the crankcase and valve train, will form water condensation on the walls of the inside of the valve covers and engine case. At the next running of the engine for a sufficient duration, the moisture will heat and convert to a gas and be blown out the crankcase vent system.
YMMV.
I wish you the very best whichever way you decide to go here.