Quickie off-the-top-of-the-head thought: Even if I win the lottery and can buy a new vehicle outright, I doubt that I would put a NEW anything into this business. Used is the way to go. You're gonna put between 80K to 100K miles a year on this van, and the resale for high-mileage vehicles is an abomination. So, your loss the first years-- no matter how you account for depreciation----- fergiddaboudit.
A used van--- whether American Slop Bucket or Sprinter/Sprinter type van-- will be cheaper to buy, a large amount of the depreciation has already happened so you won't lose so much, and you can use the difference in purchase price to set up the van the way you want it. Right off the top, you'll want decent insulation and heat in the winter if nothing else. E-track and fittings to secure loads. Decent electrical to carry your "house" load when you're standing by somewhere. It's not hard to find things to spend money on in this business.
Buying used also helps you to keep the payments-- if you MUST have them-- as small as possible. You're running on thin margins, so keeping your overhead as small as possible is the way to go here. Buy a new Sprinter-- the companies prefer we get the longest, tallest 2500 series that we can get--- and you will put a serious dent in your wallet, your payments could probably finance a small country, and you won't be getting as much sleep because you'll be worrying yourself sick over the difference between what you're making and what you need to keep going.