The way I underwrite this is using a less 10% of current rent modeling which will provide a stress test.  

Half the wholesalers out there would steam roll over her and steal her house.

This gives both parties the opportunity to test each other out (I recommend 4-6 months).

***So in one of our rentals, we tested it for Radon. 

@Sid SriramYou can utilize the FHA loan 3.5% down for a duplex, but a triplex or fourplex will have to pass what is called the "self sufficiency test." which means that 75% of market rental income needs to cover your loan payments (which include payment, interest, taxes, insurance and mortgage insurance) so it is extremely difficult to find 3-4 unit deals that pass the self sufficiency test in San Diego County so a duplex (or duplex with an ADU or SFR with ADU) will be your main options.

Starting with a duplex or SFR + ADU in San Diego due to friendly zoning laws, is a great way to get the ball rolling in REI!

Most will say it will roll into M2M but not all. 

The existing rent roll was $20,000/mo. at purchase, and we have since already increased it with some lease renewals.

what was monthly rent roll before purchase and what were you able to raise them to?

That will free up your ability to use the FHA loan program again and not have to worry about red tape rules.This will also give you the opportunity to live with your Fiance' and test the waters.