I'd love to know where to find these people to interview. Where do I go, the supermarket, the park? Also I don't think my network is big enough to hit up a significant number for a new software idea aimed at a specific niche (ex used cars sales). Those are the pieces I've never been able to put together in all my time with the Lean Startup methodology.
But the point is you can still do that on your own time without making huge sacrifices. Taking the concept of "go out and talk to people" too literally just serves to prevent you from actually finding and reaching your ideal audience.
Need to know where to start? Angel List, LinkedIn, Meetup, and the like. Write some cold emails. You can always build a network, and you should if you want to start a business.