I have said it in my thread and on the my pictures on Webshots. Thin rubber gaskets made from bicicle inner tubes make wonderfeul gaskets. Almost none of the manufactures on their trailers I have seen, seem to want to to use gaskets of any type. Gaskets prevent water from getting in near the screw or bolts holes, and protect the gelcoat or paint
from chaffing because of movemnet of attachments. I installed gaskets under every piece of hardware on our Boler
I also drilled out every pop rivet and replaced them with 10-24x 3/4" Truss Head Stainless Steel bolts (Total cost $6.00 for 100, the SS Accron nuts for the inside were a bit more exspensive) and used white plastic washers under them on the out side. Two summers ago we were in a very severe rain storm and I saw water was leaking in through all the rivets holing the cabinets in. It leaked down into the upper cabinet and the collected on top on the stove hood. When I pulled it out there were lots of water stains and water still sitting in there and down around the counter. Since I redid it, we have been through 2 more very severe cloud
bursts and I could not find one drop of water inside. The leaking rivet were also why all the curtain rod holders and some other items inside where leaving rust stains on the Ensolite lining.
Dabbing any thing on top of pop rivets is a waste of time in my opinion. There are some leak proof pop rivets available where the mandrel snaps off just above the head but there is a special tool to grind them off flush for about $400. I have used them when I had to replace a curved front panel on our Featherlite alum trailer. (I punched a hole in it) Because I did not have many to do I just filed and sanded them smooth. They are not readlly available and not cheap.
We got into a long involved discussion of pop rivets before the hack. Pop rivets are good on things like snowmobiles, trailers etc. where you are not concerned about water getting in and roting or rusting components.
This brings up another point. The chemical industry has do a good job over the years of convincing the public that silicone is the fix all product. Wrong. Having worked with many types of wood, plastics and metals over the years, I have found and had some bad experinces with silicone. I found this out over 30 years when I installed two Plexiglass skylight into out house in North Vancouver where it rains about 140 inches per year. Within a few mones of installing them I noticed drips onto floor when it rained. When it stopped raining I checked them but could see nothing wrong. To be on the safe side I caulked around the alum. frame where it joined the Plexi. Next rain storm, more drips. Finally once the summer came I got on the roof and could see a very very fine gap between the Silicone and the frame. This had been applied by the vendor. I removed every bit of Silicone and resealed them with a Grey Polybutyl caulking which didn't leak again for several years.
From that time on as I learned more about plastics and their properties, I was able to figure out what went wrong.
The co-efficient of expansion is vastly different between alum. and plexiglass, all plastics for that matter. Over a period of time with the heat, cold and water action and the difference of contraction/exspansion between the the metal and plastic the Silicone seal gives out. There is your leaking problem! I have encounterd numerious other occasions of Silicone problems.
Any time I hear some one on this forum talk about using Silicone I get a little shiver.
I hope this will provide some guidence and there are many others on the forum who have a wealth of knowlege and experince to tap into.