IMHO and my past experience it is best to ask the CG that you think you might be staying at.
I found the "rates to be all over the place" from CG to CG. Ask the Manager of the CG they have a good idea of what the average monthly electric bill is for their varied campers that stay there.
I actually made my decision on which CG to stay at based on the electric info provided to me from the CG managers. I have an unlimited budget when it comes to RV'ing but some of those CG's/resorts where SO outrageously priced for electric. I refuse to just throw my money away.
