I have seen 3M window sealer (the black goop) and counter sunk allen head bolts with washers and nuts on the back side. If you really want to do a clean job, cover the seam with the factory trim if applicable.
I used the countersank allen head bolts from Bickel across the top (the only place I could access the backside of the bolts) and used countersank metal screws on the sides and bottom of the windshield. I used a 3/8 thick rubber seal from Bickel, also. When I put my chrome on, it'll look like a factory windshield.
The nut-sert thing has crossed my mind. I have a complete set of those in all the different sizes. I planned on drilling a pilot hole to see how thick the fiberglass is in that area and then make a decision from there.