Say, no more than 2 homes per household, 1 extra for each additional adult. You want a vacation house, or a place near work? Fine. You want to buy another house and take your time moving? Fine. You want both? Make some compromises.

Or we could make the limit 5 per household - that would be excessive, but if they couldn't rent them out it would still decomodify housing, because it's people buying homes at scale that really is killing us

From there, you'd crack down locally - if you want to live in the boonies, I don't care if you have 5 acres. If you live in a city with a housing shortage, maybe you only get a certain square footage per person, maybe certain areas are primary residence only, or however you want to slice it