I have a 1" x 21" section along side of my tub -shower assembly , this was back cut for clearance for the fiberglass stall mounting screws, the trouble was that this edge was paper thin and was moving by a simple touch of the finger in this area. There is no stud to attach this piece without drilling a hole in the mounting lip of fiberglass tub. I think this area is metal or porcelan. I guess I could get some drill bit to cut through it , but I may have to drill in at an angle as the one mounting nail is angled to meet stud properly . I really don't want to tear out a 19 x 15 area of drywall unless I have to.

Can you post a picture of this?