We've had 4 in ours. I think it depends on how much time you plan to stay in the camper. If you plan to primarily be outside, then it is fine. If you plan to have personal space, and friends along, it's going to be really tight. If your kids are like mine, the window of traveling much with them is closing soon except to kid events. They start becoming more involved with other nonfamily activities when they get to high school.
I found a Class A ideal for traveling with friends through early high school. I don't think a small Class C is much better than a TC once setup for sleeping, but can have more sleeping possibilities. With really large numbers of kids, their Mom and I slept in a tent outside.
Another thought is tent + TC or small trailer + TC or small toy hauler + TC. That would give you some options other than having a massive TC. A concern with a tent is that not all campgrounds allow them which can be limiting.
If you do go TC pay attention to the width and length of dinettes and couches. The size varies a lot.
