glassing bumpers

hey i want to shave the front fogs of my golf seems to me like you guys have a pretty good idea of what to do with fiberglass and i was wondering if youd think that would be the way to go
if so how would i go about attaching it to the car would i have to make some sort of backing and attach that or could i just adhere the fiberglass right into plass????

right into place sorry

I'd make a backing and fiberglass it right onto the bumper.

I'd make a backing and fiberglass it right onto the bumper.
what kind of backing would you use ive never really done anything like this before, so would the fiberglass adhere directly to the bumpers