A number of years ago I stopped by one of the local RV dealers for a part or two. There was a fifth wheel (don't remember the make/model but definitely not a Keystone product) that had the entire rear cap taken off and quite a bit of the interior paneling removed/loosened. I talked with the tech for a few minutes and he told me that he was chasing down a bad connection somewhere. Regarding the completely disassembled state of the rig, the replied that no two rigs from the same assembly line were the same. Wires would be run differently and with different colors depending on the particular guy on the assembly line and what wires he laid his hands on.
This company did actually publish a wiring diagram, but the tech had discovered that it wasn't worth the paper it was printed on....
Sounds like pretty common practice in the RV industry. Then again, the RV industry is policed by nothing but the RVIA, the proverbial fox guarding the hen house
Eric