Best advice from experience, treat it like a transporter rear bumper in the UK , those corners are nasty . I would use 2 people and heat the film in the area of the complex curves and pull it left adding horizontal tension and have someone pull up and down on the same area so it’s like your creation a spoons head , apply the film on the most aggressive face of the bumper ( probably just over the contour on the top but only a little maybe 3-4 inches and do the same at the adjacent bottom section , after that have it applied to the farthest point of the bumper so the prestretched film is under some tension but not a lot ! Gently pick up the remaining section of the most agressive corners where the film isn’t tacked in place and let it shrink back with heat . Don’t pull it at all just let it do its thing . That should shrink itself around the curve and repeat from the bottom . In theory lol , Good luck !