I would do it. I just would. The extra kid would only be there for 1-2 hours a handful of days per month. Plus the other little kid will be going on mat leave shortly anyways, so it is a short term thing. I would do it. Now if you were talking about being over by 2 or more kids all day every day, then I wouldn't do it.

You see, the threat of being reported means nothing to me. There are tons of 'providers' who are over all the time and are never reported. Also, the ones that I know that have been reported (and a few times too mind you) have been visited and told to let go of some kids and that's it. They are still in business. No fine, no getting closed down. And some continue to take in more than 5 kids.
Also, as far as insurance, I live in a small town, so if something big ever happened that I needed to make an insurance claim for, I would be out of business anyways because word travels fast around here.

And if anyone can prove to me a case of a home childcare worker successfully being sued by a client, I'd like to see that. Now if a kid died or something like that, that's pretty extreme, and your name is mud anyways, forget about being over in numbers and your insurance not covering you for liability. Plus, I think my insurance company would take my word for it that I only had 5 kids at the time. (Since I'd only be over by one for a couple hours)