Interesting topic. I've blown the main 30 amp breaker in my Outback a few times. I would have expected the breaker at the post to go first. But it did not. This has happened to us a few times. I suppose the breaker in the camper is either a bit more sensitive to 30 amps, or else the breaker at the post just doesn't work.
No need for read-outs or anything though in my world, when I turned on that electric griddle with the water heater on electric and the air-conditioner running, the television and Dish receiver, 2 fans, and the television in the bedroom, I knew the griddle was a bit to much. Same thing happens when I try to plug that griddle into the outside outlet. I know better. I usually run an extension cord direct to the campground post for the griddle. But when it was raining that day, I just didn't want to go outside (you know???)