That's great! Did you watch the person diagnose it? Electricity isn't really all that hard once you understand the flow. I was on the right track. A "quick fix" in that situation would have been the single wire with the alligator clip going from the truck to the common ground on the camper, but that goes back to not having a tester. Whenever you have "total loss" like (since you already deduced that the fuse was good)it's usually a ground, no matter if it's the pigtail on a camper or trailer.
