Used to go camping a lot as a kid. We had a 12 man tent that web used for 3/4 of us and 2 dogs. You can walk around in it, and cook in it no problems. Wynster sattelite 12 it was.
Definitely go big, our wynster didn’t have a bucket groundsheet which was a pain if its really wet. So get one of them.
Take airbeds and a 12v air pump. You’re in the car and don’t have to carry it, so go for the extra comfort and warmth.
Edit: Take a dustpan and brush too.