The well-equipped instructor has some black circular pieces of rubber in his bag, 3,5" dia, to cover the instruments. Ask him to apply one or two at a time - not all at once as has happened to me, too.
As for the FS realism: I remember this chap who simulated flying into grass runways, and had his wife standing behind to shake his chair on touchdown. I could never imagine asking such favours of my ex!