Wire looms, aka split convoluted tubing, is good but has nothing to do with wiring connections. BTW, do not judge anything by what you see in campers and RVs, unless they are in the $50,000.00 range or above, because they are crap. They are built using the cheapest possible materials and techniques, hence the Romex. Ambulances, like all emergency vehicles, are built to the highest possible standards and meet all current safety standards at the time of their construction. Campers and RVs are built to make money and ambulances are built to save lives.
Once we purchase these ambulances they become POVs, and as such they are not governed by the same laws, codes, and regulations that they were as in-service ambulances. So, you can pretty much do what you want, however if you are involved in an accident or have an electrical fire resulting in injuries or death, then litigation will take place and the other party's lawyer will request an investigation from the State Fire Marshal's Office. They will go through the entire vehicle and present their findings to the court. Personally, I sure wouldn't want them to find out I used
sub-standard materials (wire) or improper wiring techniques, would you?
This is all just FYI, you can do with it what you want.
I'm out... Cheers ...?