I finally added a relay to prevent the Wrangler's brake lights from coming on while towing. Our bus lights are connected to a pair of extra 1157 bulbs that are cut into the Wrangler's tail light housings. With this scenario the 'bus-driven' bulbs mimic the bus, which is fine until you have a turn signal flashing and then hit the brakes. The stock Wrangler brake lights come on but are not blinking, so they wash out the turn signal.
I bought this kit:
You could easily buy a relay and all needed parts for less cash, but the one really handy part is a clip that inserts into the appropriate fuse slot, with a slot on it so you can relocate the fuse to the clip itself. This gives you a nice power feed without having to get into the back of the fuse box and mess with getting an appropriate power source. That part alone made the kit worthwhile.
Note, the 3rd brake light is separate from all of this, and still comes on whether the Wrangler is running or not. Only the main brake lights are affected.
Just an fyi post for anyone considering this.