Can a 50 amp coach work on a 30 amp site? YES< Mine does.
The Rules
20 amps you can power ONE big ticket item (A/C, Heater, Water heater, Microwave and in some cases your converter if the batteries are hungry enough)
30 amp 2 big ticket items
50 amp ... All you can eat
SOME 50 amp (And 30 amp) RV's have special Enegery Managers that monitor your usage and will turn off, say an air conditioner, when the microwave calls for power. Some (mine) do not.
There are major differences between 30 and 50 amps, but the dogbone adapter handles them well.
I have slightly modified my RV so I can run both A/Cs on many 30 amp sites.