I know this will get downvoted but, I say Throw the building codes out the window. Housing people is more important than regulations.
If it made a difference to your ability to get shelter, which would you rather choose: have shelter or live in a illegal tent under a bridge resting assured with the knowledge that there's a big book of rules in place.
The problem is not all codes are meaningless regulation, and some of the important ones are indeed expensive (and vice versa). If you yolo it, you get cases like the Grenfell tower fire, and a lot of people literally die.
This is how you get housing tenements, and SF has a history of over-paying for impermanent housing solutions (like tents in a parking lot, or cots in a navigation center).
Not all buildings in SF are high-rise open-plans. If you're imagining converting Salesforce tower, I see how that would seem impractical.
Most commercial office space in SOMA (old warehouse buildings) can be converted into live/work lofts.
If it made a difference to your ability to get shelter, which would you rather choose: have shelter or live in a illegal tent under a bridge resting assured with the knowledge that there's a big book of rules in place.