This summer I camped next to a large family -- 5 kids (3 teenagers, 2 younger kids) plus mom and dad.
They were driving some sprinter based class B, but they also towed a small travel trailer behind it. They said the motorhome was the "master bedroom" plus the sleeping area for the 2 younger kids, the older 3 slept back in the travel trailer.
The trailer had a big rear hatch with outdoor kitchen, so they did all of their cooking back there. First time I've seen a motorhome towing a travel trailer, but it looked like a good setup for such a large family and they said that having 2 bathrooms/showers was a huge bonus.
