Since your properties have significant equity and low interest rates, you could consider refinancing just enough to maintain strong cash flow.House Hacking:Consider purchasing a duplex, triplex, or fourplex in San Diego.

I don't know if this is actually in an A or B neighborhood, but would a duplex like this interest you: https://www.realtor.com/realestateandhomes-detail/116-Regent...?

Since your goal is getting into commercial real estate, it might make sense to start with a smaller rental property like a duplex to get experience managing an investment.

SFR with room to build on the lot will be much more plentiful than duplex/triplex deals.

For example, the 2nd to last photo of a random wall and floor with part of open door; what is that supposed to be telling?

So yes, you can have solid concrete walls, it's still going to burn down.I have read that worst case up to 80 million Americans will relocate in the next three decades.

Their number is available and you can call them to ask questions about the property.Why a duplex?

If you live there and are currently renting, then there still is a pathway to house hack say a duplex and better your situation.  

Is there a clause stating he can't remove the copper pipes from the wall? 

@Kendric Buford Considering a Duplex, TriPlex, or a Four Plex.