One of the challenges with a 30 amp service is the ability to use portable electric heaters. Using one heater is just fine, however when you plug in the second heater the circuit breakers in the motorhome power panel usually start tripping.
A solution to this problem is to add an additional 20 amp line coming into the motorhome.
The lower of the three plug in’s is a separate ground fault plug in which is wired to it’s own electrical source. I run an extension cord from the outside plug in a 20 amp breaker in the power service.
This works great, don’t have to worry about over heating the motorhome’s electrical system and we have heat in the bedroom.