That sounds like a good plan in many situations... But how do you handle candidates who say something like "look, there's heaps of code that I'm proud of and would love to walk you through, but it's all work I've done for past companies and don't have access (or the legal right) to show you?"

You might just say "well the ideal candidate has meaningful projects outside of work," and just eliminate the others... But it seems like you'd lose out on many otherwise great candidates that way.