I fought this same exact type of 'ripple' on my current RV. It was fixed on one side by warranty. The other side started doing it after warranty and was fixed by insurance when a flat tire destroyed the original sheet metal.
You can try more screws, more sealer, it will always come back.
The only way it was fixed was to remove the entire piece of sheet metal and reattach starting at one end. That way the bubble of pressure is removed.
Scott and Liz - Southern NM
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