Correct, no 3rd brake light. It's not required in WA, but it is in some other states. Sounds like you have a good solution with the yellow wire.
If you can avoid the loom and use the stock contact connector I think it will look cleaner.
Yeah but I am already using the two contacts for the ground and positive side of the brake light. I would only put the loom on the yellow wire that I added. It would be a short piece just to try and keep the wire from getting pinched.