Like Benihime said,go ahead and do it,but expect some uh..weird looks and whatnot. xDD
If you do do this cosplay,hell,have fun with it!
Be all weaboo and etc. I'm sure you'll get lots of laughs out of it.
I believe most Vocaloid fans that have been in the fandom for a while know about Kagami Kawaiine.
Though,hold a sign..or something saying what you're doing just a JOKE. xD