Re: rivets vs self tapping screws
I have had several buses. Probably half of my buses had the interior panels held in place with screws. I usually remove about 8-12 feet of roof, then put it back together again.
I have used both screws and rivets with good success.
+1 for rolling a sealant onto the roof after calking and re-assembling everything.
Quis custodiet ipsos custodes (who will watch the watchmen?)