I suggest using butyl rubber instead;
Rip off a small bit of it and work it in your fingers until it gets extremely sticky. You will know, as it will begin to stick even to your skin. As it is heated and worked it becomes more tacky. Make sure the gap in the rubber trim is cleaned out nicely and wiped down with something like rubbing alcohol. Then simply apply the butyl to the gap. Press it down into the cracks and it WILL be sealed. This stuff will not fall
apart or shrink and come loose over time the way silicone will. Not only that, but it works instantly. No need to cure or anything, and you can just peel it off and replace it whenever.
I don't use anything else for small gaps.
As for large objects such as holding on flexable solar
panels, or for sealing around something with edges I use EternaBond tape. ( Robot Check
) Treat this stuff like it is a deadly weapon. No joke, it is so damn adhesive you could end up stuck to yourself or other objects. Make sure someone is around to help you in-case it ever got on your mouth or something. Just saying. If you don't need to seal the edges (I always prefer to do that) 3M Very High Bond or VHB tape will also do the job.
If you have a roll of butyl on hand though, no leak will scare you anymore. Even in the middle of a downpour you could take a little wad of it and stick it over the offending rivet or crack/gap.