TG Twinkie has a good set of questions. A little more info about your trailer would help.
There are photos of the DC fuse panel, the batteries, and the Univolt (and replacement Inteli-Power) with the sofa removed in my 1983 Excella here: http://www.airforums.com/forums/f449...0-a-57567.html
. Hopefully there is enough similarity to help you out.
My Excella is a center bath, rear bedroom. The AC breaker box is in the closet across the hall from the bathroom on the exterior wall.