My rubber over plywood roof is heavy-duty enough to walk on, so I used short (2")piece of aluminum angle iron with a pair of stainless steel wood screws, sealed under and over with Dicor. A full description of my project and links to the photos can be found at
http://www.forestriverforums.com/for...ion-14096.html
Sorry, I don't have any fiberglass/luan experience, but maybe someone who does will pipe-in....