Jim,

The 80% is no secret. It has been discussed here on this site numerous times.

Power management is a must on these coaches, and when we are on 50 amp service, we can do pretty much anything we need to do with little concern as long as we are aware that sustained power usage in excess of 40 amps per leg (or 24 amps total, or 16 amps total, depending on power source) may trip the breakers. The answer however is not to step up the breaker size because everything, including our power cords is sized for 50 amp service.

I want the breakers at the campground power outlet to trip long before I have a fire due to overloaded wires.