I've wired cars and boats and houses..
Cars and boats, the wiring is commonly traced as accessories are added, and I always use color coded wire.
Houses? Well, I haven't found a good supply of color coded romex, but I do spray the inside of each junction box with a separate color of paint to represent different circuits.. Who knew that the computer, microwave and refrigerator would be on the same circuit?( I have a 70 yr old house now )
Basically, if you are going to wire it, and never touch it again, I wouldn't bother with color coding.. Trailers are not that complex in their wiring.. You might have 2 circuits in there.