To start, I rewired the brake lights to all get power from the CHMSL circuit, so they no longer flash as turn signals.
Then, I ran wires from the front, sending power directly to the turn signals in the back. That way, they only act as turn signals and not brake lights.
I used the existing reverse socket, but I put an amber bulb in instead. I used amber 3157's, but only because I couldn't find any 3156's.