My strategy doesn't involve influence by any factors outside of my control. 

R-2 is typically designated for a residential zoning, likely higher density / multi-family. 

Another business partner of mine is a marketing pro who helps investors anticipate which properties will book out well and which ones might struggle, provides some creative design tips too, if you're into STRs at all. 

Then factor in the amount that people can afford .  

Although there is the caveat that unrepresented persons in contracts leads to lawsuits at about a 10x factor versus when both parties are represented.

Lots of factors affect friendliness...Fees: Google "All About ADU Permit Fees & Waivers" for a breakdown of these on average by jurisdiction in San Diego County.

DSCR is designed for this situation.

-Is this in need of some kind of professional designation or compliance with some kind of law or regulation?

They did, 4 days later in person, and told us that we were in violation; that short term rentals (less than 7 days) were not an allowable use for our zoning designation, CRO (commercial, residential, office) and that we would be receiving a certified letter to cease and desist.

Then it can be dangerous in regard to several factors.