SPRAYLAT SIGN STRIP
Several makers of this stuff; the age-old sign version for spraying plexi signs is now owned by PPG, still called Spraylat. Not a lot cheaper than the products mentioned here.
NOTE: do NOT let this stuff 'dry out' in direct sunlight or a hot shop. If somehow it ends up on there for years, it will be very hard to remove.
I don't think there is such a thing as 'too thick'. It makes it much easier to peel.
If yours ages and becomes brittle, roll on another coat; this will moisten the old layer, and give you more to hang onto when peeling.
happy canopy'ing!