Attatching a three post spoiler on a coupe, Got some questions Options

[Legit94GT]

So awhile ago i bought a three post spoiler from coomer and have been meaning to paint it and mount it on my car but...

I am kinda concerned about having to drill holes into my trunk and possibly having water leak in( i live in vancouver/portland, it rains ALOT here) the old "gaskets" on the post are long since destroyed

Is there another product i can use that would act smiliar to the rubber stuff that use to be one the bottom of the posts?

How do i know exactly where to mount it? I mean i can get it centered by splitting the difference of the trunk but how do i mark where to drill the holes?

OR We can step out of the box on this...

What if i cut off the threaded posts coming out of the spoiler and bondo or fiberglassed a peice of metal on the bottom of the post, then put strong magnets on the underside of the trunk to "grab" the bottom of the post and hold them in place?
Im talking like industrial magnets with at least a hundred pounds of pull on each one...

My only concern with that would be rattling it lose from my subs and scratching my trunk up alot...

Thoughts?