3M tape FTW....it aint going anywhere. The amount of 3M tape you have on there prob weighs more than the spoiler itself.
One tip, I did test mount it first and traced an outline of where it should be positioned using a whiteboard marker (yes you can remove it). Once I have everything in position, I then proceeded in lining up the spoiler with the traced outline slowly peeling away the backside working my way from left to right. Everything came out perfect.