TDD, I love this question! What I would drive is what I DID drive. To me the choice is simple. A class 8 straight truck. The only thing different that I would do is either go twin-screw or add a tag axle. The class 8 truck (century) had plenty of room in the sleeper to live, but I kept the amenities to a minimum. Fridge, micro, and a small TV. I tried to run lean. I could scale 14000 in the box without a problem. A tag or twin-screw setup would have let me scale 20k. My company pays tractor rate for any load over 13000lbs, so it is a factor that may not double your numbers, but it WILL noticibly add a few cents per mile to your average revenue.
A 24 foot box would have been nice - but the 22' did just fine. A class 8 straight truck gives you plenty of room, plenty of power for pulling hills in the "lumpy" states - and usually a transmission that can get you 12 mpg on cruise control in the "flat" states.
One of the keys to success in expediting is to give yourself the ability to carry almost any load - especially in an area where loads are few and far between sometimes (that is just reality, regardless of what you drive or who you drive for).Carry extra load bars, straps, and even plywood sheets for decking loads that are not stackable. The more resourceful you are, the more money you can make, period.
In a straight truck you can haul almost anything except for a tractor sized load - and that is just by volume, not weight if your truck is properly equipped.
To make a long story short, You can always put a cargo van load in a straight truck - you may not want to, but in that rare case that it is your best option at the time, you can.
Under no circumstances can you fit a dock high straight truck load into a sprinter or a CV, ever.
My opinion from personal experience, I hope it is the kind of answer you are looking for. - X