I also saw your reddit post, just good mate.
I like the idea of @Kakmakr, so that you(we) can spread awareness about bitcoin to those who are not exposed yet. Also, if you could urge other artist to try this kind of art frescoes, that will be great.
Yes I would love to make it easy for street artists to add their own Bitcoin QR code to their works with a easy way to verify the address, I'll do a tutorial soon.