You got it half right, which is better than most folks do.
rwbradley wrote:
- If I use a dog bone to connect to a 50A service, there should be no danger as the master breaker will protect me from drawing too much current
True, the 30 amp breaker in your RV will protect you.. There is a very very very (I can't type that many verys) small tiny tiny chance the cord could overload but,,, Basically outside of an electronics lab, that is not possible.
- If I use a dog bone to connect to a 15/20A service, there is danger, as I could draw the full current and even try to draw more.
No, since the outlet will be protected by either a 15 or a 20 amp breaker depending on the wires behind it and the type of outlet.. Thus you will trip the supply side breaker instead of the one in your RV, but you are still fully protected.
In short, use of dogbones is safe.