She is transforming an existing structure into a creative studio space, seems cool, and I want her to succeed. 

That would be best option as a traditional bank wouldn’t do this I read that I can assume the existing mortgage.

Affordable Housing Incentives -While SB 9 encourages new development, it also includes provisions to protect existing tenants and preserve affordability.

Other lapses include forgetting to include utility fees in a new lease which was previously discussed with the owner but the new lease got signed by an existing month to month tenant and was not shared with the owner before the tenant and the PM signed it!

Having said that, we also have many clients we use our systems and processes for crypto funds, buying existing businesses, funding startups, hedge funds, venture capital, and even non-profits.  

Even if such a loan existed (which I doubt), once Vincent self funds all improvement costs, finance charges, carrying costs etc., I doubt he's any better off.

I simply don't understand the point of SubTo when there is a many generations old existing legal instrument readily available for use.  

Requires some pre-planning if the ceiling height exists. 

I managed STR with my sister twenty years ago before Airbnb existed.

There are occasionally opportunities for grandfathering if there is evidence of legally established conversions that were done previously, but no permit records exist to show it was done.