One of the first models I made was a crappy and simple model of a spoiler with dual wings (I'm not sure of the right terminology). I have revised it and made a far better version, including a better mounting system and a slight curve.
Print as is from the stl file and use supports.
You might need to add a brim so the print doesn't fail or paint on supports for the mounts just in case.
Use double-sided tape to mount the spoiler
The author marked this model as their own original creation.