came to me with a vinyl belly band - the same trim that is around my door opening. I was not fond of the look and I wanted an aluminium one like everyone else, so I made my own. As JKM said the band covers the flange where the two halves of the shell come together. the band is riveted from the top into the flange and does not pass through the bottom of the aluminium channel. As for how close it is to the wall, I'd hate for you to do a close inspection of mine! The wall of a Boler
I am doubtful you will find it easy to change how close your band is to the wall. You have to put leverage on the aluminium channel to get it close to the wall so you can drill a hole through both the aluminium and the fiberglass flange (be sure to not let chuck of your drill hit the fiberglass) then you need to set your rivet (again you are working really close to the wall of the boler
, don't let your gun scratch it). I am pretty particular and methodical and I have to say, I have more space in some stretches. That being said though, they don't bother me and I have no plans to try and do it again.
If you do try to remove and reset the belly band all of your rivet holes will shift alignment, you will need to glass in most of the holes in the flange.
Good luck, let us know how it goes.