Hello and
to everyone who goes camping with kids.. I cannot imagine childhood without outdoors fun and camping.
We (one large & one small adult) just got back from a long trip with our simple 4x8 lightweight camper-trailer. In my opinion this is a perfect thing for a single adult with a young child. And a dog if you have one. I would say just bring a tent for the older kids as the others have mentioned.
We were one size too big for this trailer, but here's why light and narrow is great: I am small and skinny and I can roll and move the trailer as needed. You don't need help to hitch it, the intimidation factor is minimal. You just get close with the car and bully the trailer around to where it needs to go. Plus the narrow width is a breeze to tow and it tracks well. If it's your first time towing a camper down the highway you'll probably appreciate that as much as I did.
However for warm summer nights, my favorite is still going to be a tall family tent for that cool roomy space... and air mattresses for the old bones.