Full disclosure: I don't have toe overlap, although when I get my next pair of shoes, they'll be larger, and I probably will - I have less than 2 mm clearance now.

But this guy (Martyn Ashton) has toe overlap, which he mentions here (the trials video has been around before, but I never posted a link to the text, which I had to dig for).

I certainly can't ride like that and don't expect most people to - and Ashton mentions the toe overlap because it was something that even he had to adjust to - but it's an indication of how little a problem it needs to be.