RE: Attaching Giant scale Windshield...?
Back up your balsa with a couple little pieces of pine or bass wood. Screw into that. CA the holes and run the screws in and out a couple times. CA the holes again. That should keep the screws from stripping out.
Use trim tape. After the glue dries, you want to trim out the windshield with some 3/8" trim tape. Clean the covering very well first. Get all your fingerprints off and get all the oil and dirt off. Apply your trim tape.
That should hold it.