Barney,
The area to the right of your shadow (you must be standing closer to the trailer edge than I want to be)looks very much like the rear of my trailer. It is hard to tell from this perspective, but my end strip might be taller. It does collect a lot of water. And the caulking was definitely lifting at its junction with the ladder post caulking, which looked like a likely spot for a leak. A layer of Eternabond tape sounds like it would be a good final solution for a leak anywhere on the roof. Thanks again for letting me know what works!
JRMunn