Sorry Miker for the flip response to your question. But you did say all thoughts welcome. When faced with carte blanche... I guess I just have no self control.
Charles' post help clear things up. Most expediters would consider a straight truck to be a dock high vehicle, over 10,000# GVWR and suitable for over the road use.
Generally anything under 10,000# GVWR is considered a van. These include cube vans like U-Haul and Penske rent, Sprinters, Aerocell and of course the scourge of the industry, the basic Ford or G.M. van.
There is a gray area. There are vehicles with dual rear wheels, a GVWR over 10,000 and are not dock high. Check out the recent post in the Newbies Forum titled Need Direction by Markin 8342.
There are no perfect truck set-ups. What works for one may not work for another. A husband/wife team may trade cargo space and weight capacity for a larger sleeper with more amenities.
Another might choose greater freight space and weight capacity over sleeper size and opt for a cabover and a large box.
The same is true for the van segment of the industry. Although it may be more difficult to put together a unit that offers a large freight area, living accommodations and the ability to legally haul 2500# all while staying under 10,000# GVWR.
So to answer your original question about putting together a (straight truck) I will use the term van, here is what I have been mentally building:
G.M. cutaway with single rear wheels, 12' box with inside dimensions 72" high and 74-76" wide. Something along the lines of a Bay Bridge, American Cargo, Rockport, etc.
The trick is that for my purposes it must weigh less than 7000# with all my junk. I would like to be able to haul 2500# legally and G.M.'s SWR chassis is rated at 9600# GVWR.
I'm still in the research phase and have at least a year before I get too serious.