We had a 1989 Pace Arrow (major POS) that had the same issue. I bought trim molding that the wife liked, stained to match the interior, trimmed it to fit snuggle in place matching the bow in the ceiling. Drilled through in 3 or 4 places and used brass screws to secure it. Place them about every 2 feet.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot