Jason
I do not do well on phone calls (hearing loss), so I will try to give you a quick synopsis of motorhome electric panel wiring. A 50 amp service to an RV is actually two 50 amp circuits wired into a breaker box (100 amps usable power). I will use my 2006 Monterey as a classic example. My front and rear AC units are wired off of 20 amp circuit breakers one on each of the 50 amp circuits in the main breaker box. My inverter/charger is wired off of a 30 amp breaker on one of those 50 amp circuits. Other heavy draw items also have their own breakers in that main box (washer/dryer, hot water heater, refrigerator, engine block heater, etc...). So, the inverter/charger only has 30 amps to work with. That 30 amps is additionally broken down in a sub panel with multiple 15 and 20 amp circuit breakers. My microwave is on a 20 amp circuit by itself. The entertainment stuff (TV etc.) is all on a 15 amp circuit breaker. The remaining electric plugins in the living area are wired into a 20 amp circuit breaker. If I plug in a space heater into one of those plugins, it will consume up to 15 amps of the available 20 amps of power. If I plug in a second space heater into a plug that is on the same breaker, I am trying to draw 30 amps from a breaker rated at 20 amps. Even if I plug the space heater into a plug that is on a different circuit breaker in the sub panel, I am now drawing the maximum rated 30 amps from that breaker. If I turn on anything else (microwave, TV, whatever), I have dramatically overloaded that circuit. The sub panel has multiple circuit breakers of 15 or 20 amps each, BUT, the accumulated power draw from all circuits in the sub panel cannot exceed 30 amps. In the same way, the accumulated power draw from all circuits wired off of each side of the main breaker box cannot exceed 50 amps. Since the engine block heater, refrigerator, washer/dryer, etc..., are wired directly from the main box, they provide potential power sources to use for aux. power draw to avoid the limitations of the 30 amp breaker attached to the inverter/charger. That is kind of an over simplified description of motorhome wiring, but I hope it makes sense and helps you understand what is happening.
Richard