Welcome! We're a friendly bunch and sometimes, our advice is even helpful. *grin*
Sounds like you have a BIG project in store. My trailer is much newer and smaller than yours, so I don't know that my battery box is the same. I don't know of any fuses in there though. Were you perhaps talking about the two Circuit Breakers (CB) that are usually in there? If so, Post#10 in this thread is how mine is wired: http://www.hilotrailerforum.com/f51/...ry-wiring-116/
I think it's more clear than a photo.