This is the best idea I've got so far about how prevent problems when raising money from somebody close to you. Another way to do so, is to remaind them that the round is called Friends, Family and Fools not for nothing.
That being said I think there is more than enough interest from just those Hacker Newsers reading this thread to show that this would definitely be a popular blog post if written.
With that in mind, go for a $100 note instead of $50 if you decide to do this and write about it as that denomination would make for better linkbait as a blog post title.