Similar problem here in Oz. (Hot sun - wrinkly film)
I've given up on plastic film for that very reason - learn to cover with 3/4 oz fibreglass cloth and your problems will be gone forever! (On solid surfaces anyway!) Also, more ding-resistance.
Most people baulk at the idea of fibreglassing, but 3/4 cloth and WestSystems epoxy is EASY to apply and sand, and you can then just fill and spray it with auto cans if no airbrush.
NEVER wrinkles, NEVER lifts at edges, TOUGH, STRONG.
Food for thought!
Cam