I don't have a schematic, but can tell you the wiring is impossible to re-do without gutting the trailer and taking the interior skins down. All the wiring - 12v
and 110v is run behind the interior skins through the ribs (with grommets protecting the wires). When I took mine apart, I found that the junctions were all butterfly'd together without junction boxes. The work was well-done and none of the connections were loose, but it makes it impossible to simply pull a run of wire from box to box.
Unless you have serious problems with the wiring, you might just want to repair and upgrade only those areas you can access without taking the whole trailer apart. You should be able to fix any connections at the outlets, lights, your panel and the 12v
fuse box. Any wiring that is not run behind the skins is likely an addition by a previous owner that you should examine carefully for problems. The stuff Airstream did held up very well in my trailer.
Here are a few photos of what it looks like behind the skins. Notice the loop of unused 110v wire between the two windows? That was in the kitchen. Looks like Airstream left that in case someone wanted an extra outlet just above the stove in my trailer. The sharpie marks are mine, but there were wax pen marks from the original electricians that showed the intended paths of all the wires.