I know that you can have light, bulky loads, and heavy dense loads. My problem is that the big (by my standards anyway) box invites you to put something in it, and seeing a payload rating that is less than my present standard 2500 van is capable of puts a damper on any desire to have that big box.
Of course, if you're doing big volume/low weight loads then an under 10K cutaway might be just what you need.