Now that you put it that way, I think I would be suppose to register as a business if I am making any income privately. Something traditionally viewed as not a fun process with the system we have. Damn complications; I like to write code, not manage a business.
I do understand what you mean. It's better safe than sorry, and I guess I was just hopeful about keeping it simple. What about writing a series of general terms on a webpage, and ask the client read and agree to the terms before hiring? It could relate to what defines the job as being finished, and such things about terms of payment. I'm not sure what entails a legally binding document though.