I'm trying to figure out who guaranteed 1500 miles a week. That would be great if it could happen, but the facts are quite a bit different. Some weeks you make a killing, other weeks you get killed. It's part of the business cycle, and it doesn't matter what size vehicle you drive.
A word about that Sprinter, fella. You're in way over your head with that machine on payments, and now you're gonna get bitten in the posterior when it needs big maintenance--- which it WILL need sooner or later. My '05 loved to eat belt tensioners, and you could hardly visit the shop to have it replaced without spending 1500 or better. Bet on a couple of other belt-related items needing attention too--- we put an enormous amount of miles on these things-- and you'll be lucky if you don't spend two grand every time you go in. Another thing to watch for on older Sprinters-- I don't know about the newer ones, maybe they fixed that-- is "Black death" that hits your fuel injection system. Another thing, the glow plug system on mine wasn't without problems, so a rough first start could be counted on as like as not. It's a Mercedes, so when you get repairs you're going to spend money like it's a Mercedes. Get used to the notion, it's part of the deal you signed onto when you bought that machine.
You can make money in this business with a van, even though there are a lot of us out here. You won't get rich, though, if what I see is any indication. You sure won't get rich paying more than half a grand in monthly payments before you do anything else.