50 amp cheater

You're not wrong, but your first scenario of 50 amps on the neutral is within the design specs of the standard 50 amp 120/240 volt circuit used in motorhomes. The neutral is sized for the maximum 50 amps that would be seen if the entire 50 amp draw existed on one hot line, with zero draw on the other. An unlikely scenario at best, and one that also covers your second scenario, where 60 amps theoretically could be applied to the neutral, but in normal use is quite unlikely to occur. Even if it did occur, the safety margin of the wire rating would still handle the load.