The three of them could not have slept in that little over the truck van. Tent? Maybe. I just can’t imagine any 23 year olds camping with parents.
We just did a 4 day trip in a converted sprinter van with my wife, my 26 year old and my 22 year old son (who is more like a 150 pound toddler so he didn't get a vote). It went great, we all had a grand time and none of us got into a fight. It can be done.