Is your Classic different than ours...
The two rectangle openings are vents for the battery box and need to be open.
I have sealed the top edge of the lower belt molding with PL roof flashing sealant from Home Depot. The same molding above the rear bumper and along the side at the rear storage compartments.
"Sticks & stones can break your bones...and hail will dent your Airstream"
So when is this..."old enough to know better" supposed to kick in?