I think I can serve as the poster child of the most people in the smallest trailer for the most years.
Me and the wife and 3 kids now 10, 12, 14 in a tiny single Axle hybrid. 17 feet long ball to bumper. Main body 7 wide by 13 long, plus front and rear tent beds.
We are mainly "long weekend" campers, the longest ever was 6 nights.
We try to spend as much time as we can outside, but sometimes weather makes that difficult, but we've been lucky overall.
Given my choice, I would make the bathroom and refrigerator just slightly bigger, maybe starching the trailer 2 feet total, but that's it!
I love that I can get into any rustic state park site, and can squeeze it next to the house as a man cave/ guest house