I was told by an independent BMW mechanic, that the switch should be just a bit more tight than hand tightened, like you can really get your hand in there !
Also suggested putting a bit of oil resistant sealant on the threads, seeing as how the aluminum washer isn't going to be pressed on as hard, so sealing could possibly be an issue .
I think the pattern part from Motobins is the way to go, we just need a long term test report from Monte .