I would vote for the tent as well. I had just shy of 20,000 miles and many weeks in a 19' trailer with 5-6 people when I was younger. We would all stay inside during single-night stops where we wanted to get moving quickly in the morning, but anything longer and we were fighting over who was going to be able to stay in the tent. That included times when the temps dropped well below freezing, high winds, thunder storms, hot weather, etc.
I know given a choice now as a not so young adult I'd still pick the tent over sleeping in an aisle-way as well for additional space, privacy, and sleeping hours flexibility. Have you asked the guests of honor what they would prefer by chance?