Looking further this evening, I found a 4-square junction box where the trailer lights wiring and the breakaway switch wiring terminate. And as I suspected, I found my mysterious red 8 ga wire in the box as well, wired in series to the breakaway switch. So I have little doubt that the auto reset circuit breaker was previously installed at the location of the three red wires.
I do question why it was removed. Aparently it was like this when the previous owner took possession. I notice that the breakaway cable is frayed and broken and in need of replacement. I don’t know if this is related.
Question: Would the breakaway branch circuit conductor go on the line or load side of the auto reset circuit breaker? I would suspect it should go on the line side like a fire pump.
Thank you all for you contribution to this thread. Your help and patience is greatly appreciated.