That's one way of doing things. But the punch won't give a clean hole which might be another problem... there's got to be a better (though not necessarily simpler) way...
I'm thinking that craft stores probably have some small hole punches.
I would make a jig that looks a bit like the top of a castle wall
____ ____
___| |____| |_____ ( I know, nice ascii art)
where the notches would be just the width of the punch and deep enough so that the film gets perforated at just the right depth.
You lay the film down on the plank, attach both ends with binder clips and punch away.
That would probably work better and its not more complicated.