I don’t know if you had plans to do it already or not but when I did my trailer wiring, I wire loomed everything and installed connectors for easy plugging and unplugging. It has made life much easier when a light needs replaced and eliminated much of the wiring issues many have due to chaffing and what not that many trailer owners complain about. After the wire loom was installed, I electrical taped the entire length of the wire harness as well.
Of course that’s the best way to do it, but are you crazy? Do you expect me to spend an extra 15 or $20 in fabricating this tractor trailer to make sure the thing works?
Seriously, I try to do that level of detail at critical points, like where the trailer connectors are. As described next, I always go to a good level of detail on functionality and durability, but I’m not too concerned with cosmetics for things that are concealed.
As regards light replacement and such, I always leave a good bit of extra wire, and I curl it up and hang it off the frame somewhere in mid air with zip ties, no stress. That way, if I do have to change a light or such, I’ve got plenty of wire to just clip and replace. With the mild leather and no salt in Georgia, that has proved plenty adequate.
I use my best eagle eye to spot any places where the wire may chafe, and I make sure there’s protection, whether that is wire loom, a split piece of rubber tubing or whatever.
As far as hanging the wire, I generally use zip ties to hold it close and steady against a smooth part of whatever. Sometimes I use a short piece of wire, shape it like an omega, and a zip tie that to the body of wire and use the resulting loop to attach it to a frame part.
When I run through a metal part, when drilling the hole, I always file it down. Then I either use a grommet, make a sleeve out of tubing, or I double or triple wrap the wire, with friction tape, and when it goes through the hole, I put a little silicone around it to keep it from moving. Usually, no motion, no wear.
Overkill answer, just for anyone else who might be reading this it is just starting out.
Looping back around, are usually take a bunch of wire, losing, wire, connectors, etc. when I’m out at the scrap yard, just to keep a supply at home. I went through most of that building the missing Link and the 97 semi. I’m way overdue for a trip to the pull-a-part. It was very hard for me to go buy a new receiver tube yesterday when I could get a whole picture assembly for the same price, but the deadline looms.
Get it? Looms? Hahahaha