Oh my gosh that's so fab! I was thinking of doing the same thing, but mostly because people tell me that I really do have one, and it hurts, so I was thinking I would paint on a proper mustache and tell people "Ha! yes I have a mustache, and it's much better than yours! So there! :p " But now that you've posted this I actually think it would look pretty cool! :)
Reminds me of that scene in life of brian where the women bought fake beards so they could go to the daily stoning. So bereft of entertainment in that time...