I've read about various primers and sealers for repairing ripped drywall. Mostly people are asking advice on how to make the drywall paintable or paper-able. But I only want to recover my shower stall with fiberglass sheets. The damage was caused by tearing off the old tubsurround. Will the wall board glue stick to the sealer? Maybe I should just skim the area with mud a couple of times, sand and prime?