I'm pretty skeptical that you'd be able to make a Bullitt pay for itself. They ain't cheap. Finding enough customers would be tough, and the only people who would actively want services delivered by bike are probably up in Wicker Park...way too far to commute on a Bullitt.
Maybe you should do what I did: I wanted a cargo bike for years, but couldn't justify the cost. Then we had a kid, and suddenly the Douze looked a whole lot cheaper than a minivan/SUV. Problem solved!
That said, if you're willing to take the risk, do you have any other skills you could combine with the bike? How about cooking?
Cykelkokken in Copenhagen does a good business; I could see Chicago yuppies paying significant money for a tour and an upscale picnic by the lake.
Or maybe something like gardening or painting/handyman service might work OK, if you could undercut the other guys who are running vans. That'd be hard work for not much cash, though.