If you have a large Ace, you will have a better chance that they will have them than a small store. Personally I would use at least four studs. More if you think it is needed. Try not to put any out in the middle. When you tighten them it could distort the 'glass a little.
Be sure to sand the inside of the glass panel with a heavy grit sandpaper like 80, where you are going to put them. Ideally the resin sticks better if you sand deep enough that some 'glass fibers are exposed.
Brush enough resin on the fiberglass mat to soak it good.