First thing you need to do is determine what you can tow, which is normally limited by the cargo capacity of the tow vehicle. Whatever you buy should have 10-15% of its weight on the tongue, which becomes part of the cargo. Then you add 5 people.
So far as the cooking and bathroom amenities, the smart thing there is to defer to your wife. If she doesn't like it, she won't be happy and then no one will be happy. Chances are she will be the one to deal with the logistics of meal prep & taking kiddos to the bathroom---and if you do very much of it you will come to appreciate a handy toilet.
If you don't want the TV & sound system, don't use them. I've never used them in a camper either.