Well speaking from western Canada and because I have a rig like yours it sounds like, that calls for 50amp service ( cable size) I have yet to ever use 50 amps of juice.
The campgound we are in is old and a mom and pop place where there are only a few 30 amp sites and 90% of the sites are 15 amp.
They were asked why they haven't upgraded the power system and the answer was easy $$$$$$$$$
On another note I don't have two AC units and hardly ever use the one I have. The only time we pop the breaker for our site is when it is cold and we have to meany heating until a of one type of another plugged in.
So....
Around here there are no campgrounds with 50 services at all, and there are probably 20 campgrounds with in a 75 mile circle. There is a new private campgound being built and I would bet they have 50 amp services, but at that place your buying the site to put your rig on.
In bigger centres closer to toureststy areas or newer ones I would bet you could find some, but the old mom and pop places I bet not.
Best bet would be to order a tourist guide for the area / region you want to visit and then send the campgrounds a note or phone them and ask about there power and other services your looking for.
But again, I'm from the west side of the Great White North, it could be a lot different back east.
Soup.
