I am attempting to install a frameless shower door on a fiberglass drop in shower. The shower door weighs about 45lbs and I am afraid that it will pull out of the shower frame. The supplied screws are 3 #8 2inch screws w/plastic anchors. Will this be enough? Because the face of the fiberglass is about 2 inches from the actual wall and the screws will not even reach the wall I am afraid it will pull.