[quote author=BrandonB link=board=1;threadid=848;start=0#msg4863 date=1082497175]
Would the sand harm anything at all?
[/quote]
I wouldn't think so. All you are trying to do is provide some texture so that friction would keep the mirror from flopping down. If it didn't work, you could just wipe off the sand and vaseline and be right back as before. My professional judgment, as a lawyer, not an engineer or scientist, is that sand shouldn't harm anything and should be reversible.
And, as a preemptive strike to the lawyer jokes, yes Brandon, you'll have to ask yourself: "Do I really want to take the word of a lawyer when it comes to working on my car?" ;D