It was fuse #22. Sounds easy except that I explored every fuse box I could find. Whilst reading the Ford Manual yet again, I found that 2 pages had stuck together and when I got them apart there was a diagram for fuse/replay locations under the steering wheel and Fuse 22 is towing turn signals.
Why didn't I see that fuse panel before? 1. I don't have a door and I'm not svelte. 2. I had seen the circuit breakers and checked all them. But on top of them is another panel, that has yet another cover on it and underneath it were a buch of mini fuses.
So lessons learned: read the manual and make sure you see ALL the pages; know that there is a big fuse panel above the circuit breakers under the dash; the tow plug has its on fuses and operates independent of the coach lights.
Thanks for all the help attempts! Steve