Any body men? Question about prepping FB

Have included a pic of my stalker bumper.. you see where the two fiberglass pieces are joined together, there is a little lip that goes around the bumper..

I'm wondering, does this bumper have to be bolted up to the car, sanded and worked with the fenders, then painted? Or can i sand the lip off smooth, prep the rest of the bumper, paint the bumpers off the car and then install?

I can't see too much of a gap occuring

Thanks

Ok thats what i was thinking.. thanks