I know it might sound counter intuitive, but have you considered not running things directly from the battery? Instead pull them to the 12V wiring panel inside the trailer. I did this, replacing the run from the batter to the panel (4ga) and replaced the 12v panel with a bigger one. Solved all the 12v problems I was having because of corrosion, 5 connections plus the generator at the battery, and a cheap 12v panel. It's also cleaner now, and easy to work on with only one breaker style fuse at the battery.
At some point it's easier to just rewire rather than continue to grow the rats nest at the battery. Up to you because every situation is different, just throwing it out there.
