Okay, I have been fixing leaks and I have to make a couple of obvious observations and hopefully some helpful suggestions.
Please excuse the long post and ignore my ramblings if you already know all this. It is intended to help those who don't.
First, my old wood boat days taught me a simple lesson... water runs down and will take the easiest route to get there.
This is a simple concept and most of us know this but it is often forgotten when trying to fix a leak.
What does this mean or have to do with sealing an aluminum travel trailer?
Simply this, give the water an easier way to go and it will go there, even if it is outside.
Please do not think you can glob more sealant on and make it water tight, it will fail. Water, gravity and time will outlast you and your attempt.
Study what you are trying to seal and where you would like to route the water.
You may find drilling or cleaning a drain hole will allow the water to continue it's downward path in an area where it will not cause a problem, like outside.
Okay here is a big one, what should you use for sealant?
Silicone, bathroom caulk, epoxy, all are fine for their intended purpose. Unfortunately that purpose is NOT for an aluminum trailer, parked out in your parking spot.
Use a commercial sealant designed for aluminum that is exposed to all of nature's elements, not something designed for your bathroom or kitchen.
I have used Vulkem and TremPro with good results. You can decide for yourself what sealant you prefer.
It is much easier to achieve water shed than water proof.