How do you handle negotiating a job offer where there is no job description and no salary range defined on paper in advance?

I’d play the game with him. Submit a fantastically high salary requirement for the expected fantastically high expectations. But don’t do it as satire, or a joke or biting commentary on his method of hiring; do it straight up: “I’m going to deliver this and you’re going to pay me that.”

They say one should never state their salary expectation up front. Supposedly the one who goes first loses. That seems like a stupid game to me.
Do homework beforehand so you know what that position should pay in your area. Then make a range and present that. Make it high.

GO to the interview, talk about the job, tell them what you want for that job. Salaried jobs are often more work hours.

At the interview is where the employer should tell you what the job entails. I wouldn’t expect to be asked to discuss salary without some idea of what the job entails.