Can a total RV newbie be a campground host?

For learning the driving and the basic systems management, a couple of hours at the most. Remember, first-timers buy or even rent these things and get by just fine with the very brief introductions from the dealers.

The people-management skills that you used as a teacher, coach, and realtor are much more relevant for camp-hosting than your RV skills. You aren't going to be expected to drive anybody's RV or help them with it. When I graduated from tent camping to a Class C, it was just heaven!