I'm not sure I understand who wants one like that without a toilet or cabinets.  Maybe someone who owns one will post.  I could see potentially if they made tie downs to hold containers, etc for removable storage.  However, I do have friends that built their own frames inside aluminum toppers for hunting.  I don't know if that model would support weight inside off truck or not.  Support by the tailgate is kind of cheesy.
I'd prefer a Four Wheel Camper popup shell instead.  For the hardside, a Capri Camper like this one 
http://capricamper.com/models/retreat/ is similar with a bit more finish.