I removed the rivets ,most were broken off anyway.
The rivets use a steel mandrel. Bound to fail sooner or later.
Also riveted from the inside. Poor design in my opinion.
I Drilled the holes out with a 1/4 drill bit . Used 1/4 stainless steel bolts from the outside.
Lots of 4200 sealant with a medium stainless fender washer and stainless lock nut on the inside .
My wife held the bolt on the outside and I used a Dewalt driver with a socket on the inside to tighten them down.
Cut remaing bolt off with a cutting wheel .
Then with a vinyl glove on my hand, covered the inside nut and washer with 4200 to give them a smoother finsh.