You can simply impregnate the awning or boat canopy with Sprayhood & Tent Protector. If necessary, wipe the window film immediately after impregnation with a damp cloth.
When this impregnating agent dries, it can leave small spots on the windows. These can easily be removed with Ultramar's special window cleaner.
In our special sail & tent laundry, we use this impregnating agent to impregnate and waterproof all awnings, boat covers and catering parasols. We do this by dipping. So with us it also gets on the window film and that is never a problem.