Howdy, Bill!

Working with material that thin, I would think that a very sharp chisel 
led into a knife edge at the center and guided by a 45° block would be 
the answer.  Your V-notch, following a rule of thirds, would have to 
leave 1/16" uncut.  That's mighty fine work that I wouldn't attempt with 
my clumsy skills, but I have no doubt that you will pull it off.

Please take pics and post them when you tell us how you did it.

Bob Hutchins
Temple, TX, USA