Thanks all for the feedback and thought provoking questions ... days got busy and didn’t have a chance to post until now. I wasn’t able to troubleshoot the problem before our Thanksgiving camping trip (Tyler State Park), but because everything is fine on utility power, we had a great trip.
I’ll cut to the chase... the one thing I changed this trip was that didn’t select battery power for the refrigerator while traveling. The fridge was turned off. The evening we came back from the trip, in our driveway with the trailer disconnected from everything, I tried the lights and they worked... everything worked on DC power (water pump, status panel, etc.).
So, my theory is that in the several trips prior to this one, where I was attempting to “cool” the fridge while traveling, the battery would discharged to zero. I assumed the heavy-duty alternator, part of the Ford F-150 tow package, was able to recharge the battery sufficient enough to keep up with the electrical demands of the fridge.
The one caveat in this theory is that the day before leaving on the Thanksgiving trip, in our driveway with the trailer disconnected from everything, I connected a freshly charged battery (battery kept on trickle charger) to the camper and tried the lights... no joy. So, I don’t know if maybe there’s a period of time that has to pass before the DC voltage is switched on by the inverter or what.... but, I connected the battery, flipped the switch, and nada.
After we came home, the trailer stayed in our driveway for about 4 days while I took my time cleaning up and winterizing and the battery power was functional the entire time.