I have ordered some Parafilm M but, I have used this method with GREAT success....
First off, you must have Novus plastic polish! I paint the canopy, by hand, with no masking. I let dry for about 15-20 minutes. I then dip my most pointy brush (I bought a special one for this chore) in thinner. Roll the brush on a paper towel to remove as much thinner as you can. Sort of like getting ready to dry brush. Then use it to "erase" the paint from outside the canopy lines.
Once all excess paint has been removed, I let dry for 30 minutes. I then wet a soft paper towel or toilet paper with Novus 1 and buff the canopy until it shines. Thinner cloudiness is gone and the canopy is ready to go.
I HIGHLY suggest trying this on a scrap canopy first. It's a matter of letting the paint get almost dry before erasing it.