Proposed carrying costs? 

Here is text taken from the HOUSABLE website for Oakland:Utility ConnectionsCategory One: No new or separate utility connection shall be required.Category Two: A new or separate utility connection may be required, but the connection fee or capacity charge shall be proportionate to the burden of ADU on the water or sewer system.Here are definitions of the ADU categories from the City of Oakland website:CATEGORY ONE ADU: Involves either conversion of space within an existing Single-Family Dwelling, or conversion or rebuild of an existing accessory structure; includes no expansion of the existing building envelope other than up to 150 sq. ft. for purposes of accommodating ADU access and egress only.CATEGORY TWO ADU: Involves construction of a new detached or attached structure, including an exterior addition to an existing structure to accommodate the ADU, in conjunction with a proposed or existing Single-Family dwelling.It seems that Oakland is making things confusing with the language they are using, but I still believe that my original interpretation is correct based on the State Assembly Bill. 

In the H.R. 3936, Built in America Act, it was proposed to extend the 100% bonus depreciation until January 1, 2027.

Also consider the risks of what you propose for yourself.  

Six Areas of Focus:Florence OR - Proposed regulation but nothing formal yet..within city limits properties are eligible for STR usages with a business license to remit local occupancy taxes. 

come up with good numbers and interesting proposals for investors.  

Legally what you propose should be feasible (I am not a lawyer). 

How would you propose they "Protect" their deals?

Online it says there is currently no rent cap, but there is a new law being proposed that caps it at 10% and for new tenants, only 15% above what the previous tenant was paying.

This will be very challenging and you will need to propose a new zoning regulation that will allow your property to be permitted in the zone that currently does not allow multifamily.