Nutserts would work great. Since most of the load (Lift) is on the front edge, and that part is screwed to the windshield frame, the rest of the top is just shear load, meaning that it's not an upward pull but more of a slide. I just ut a soft top track on my CJ and used 5/16"x1" lag bolts. It's solid as solid can be. I wouldn't want to take it on and off a lot, but down here, I'll never need a hard top so the track will never get taken off.
I did see a fiberglass body where the guy took a Dremmel tool and cut a slot just under the lip of the edge of the outer body where the two panels meet. Then slide the flat nuts, that came with the hard top, in place.