Unfortunately, for a lasting solution to water seeping in around rivets, the proper fix it to remove the rivets and hand buck in new ones. When I first took my AS to Jackson Center, we found that the seam where the front cap is attached to the roof had water seeping in around some of the rivets. The discovery was totally by accident. I wanted to have a cellular antenna installed just in front of the Fantastic Fan. I knew that there was a leak around the front window, which JC repaired. The final part of that repair was to do a water test, and it just so happened that the bezel for the fan housing was removed just prior to the water test. The newly sealed front windows passed the test, and that's how the leak was found.
JC told me that the proper fix was to drill out the rivets and hand buck in new ones. In order to do this, however, they had to gut the front of the trailer (remove the gaucho and the interior to expose the seam). I elected to have this done, and I don't regret my decision.
My experience with silicone on RV's is not good. I mentioned in a posting I made on this topic before that I had had an AS moho ('94 LY), where the PO had put a bead of silicone down to seal the roof seams. I had water leaking in (the proper term should be gushing in) and I went to our local AS dealer. His tech got up on the roof with me, and while it all looked good as far as I could tell, he reached down and put a fingernail under the silicone and the entire bead lifted right up.
1987 Excella 32-foot
1999 Dodge Ram 2500HD Diesel