If you're looking at a camper with interior amenities like stove, fridge, table, storage, beds, etc., I doubt you're going to find anything usable, sturdy, and in working condition for that price. I hope I'm wrong and you're find a great deal.

However, you also called it a shell. A shell is just the exterior with no amenities inside. If that's the case, $400 is a realistic price to find a used shell for. But you won't get all the things you say you wanted. However, this is a fine way to travel/camp.

In either case, I'm unconvinced that you will be able to get all those kids and dogs in there and travel safely and comfortably.

Actually, I'm more concerned about safe traveling right now. How can you fit 4 kids and 2 dogs plus you, the driver, in a Ford Ranger safely? Even if you put the dogs in the camper/shell while driving, are there enough seatbelts for the rest of you?