The fuse block is an option so may not be there.
The colors of brown and red should be correct.
Trace the green wire (camper running) and see where it goes. The red and brown should come out of the same wire run pathway. I would need to go out and verify, but believe it runs down into the cavity by the front of the camper down under the ground strip.
In regards to your step, look carefully in the carpet and you should find 4 screws holding it down. Once you find one, you should know where the others are.
Sending you a pm with my email. Please email me something and I will send you a much more detailed file for the wiring. It is for a 2008, but was told by Lance techs the info is still pretty close to what they do.
After I eat, I will also run out to the storage yard and look at my camper a bit closer to see exactly where the wires run. It is an 815, but the floor area is built basically the same.