It was the converter. As soon as I unplugged it, the breaker no longer popped. I should have known. It was making ugly fan noises occasionally just before the trip. Got a new one at Camping world in Grand Rapids, MI. All working on the electric front.
Fyi, that circuit has the converter, the fridge, the two plugs on either side of the front bunk, the plug at the base of the sink vanity, and the one at the bed. Maybe more...
I went in through the outside storage compartment. It's a tight fit, and a 5/32" allen wrench will live back there forever. Gotta know when to cut your losses. I think that access mod is a good idea, as the converter is barely out of warranty... I expect to replace it again in a few years.