I'm drafting a lease for him and it's a little awkward but I know it's the best course of action. Yes, it is awkward, but also a good way to open a bigger converso, so do it. Then store it somewhere findable. Also offer to revisit it in three months after you've actually lived together a bit. You will discover you have different noise tolerances, different scheduling priorities, different mess tolerances. Word definitions will have changed.
Example: I made an agreement with husband #2 that he would pay for everything. All I had do was be "a ray of light shining in a dark place." He kept his part of the agreement, but I couldn't keep mine. I didn't know at the time that some darkness won't let the light in.
If we were to renegotiate, I'd be more specific. Fortunately, that train (renegotiation) has left the station.