Office vacancy for San Diego as a whole is around 9%, but I would be concerned about the age of the asset (probably some deferred maintenance to consider even though it's well maintained) and that its off the beaten path in Poway. 

Like Mihir mentioned, I highly recommend you consider taking a leap into multifamily investing rather than purchasing an SFR.

I've known him for ages, and he is not interested in the real estate.

I don't know really where to point you, for the reasons mentioned above, but finding the right person is your key.

;<))The price is completely dependent on income and adjust for age or lack of maintenance and deferred CAPEX.

Disclaimer, I haven't used this, or even purchased my first property yet, but Integra Realty Resources is mentioned in the bigger pockets podcast as a source of cap rates, I think it was episode 265 with Andrew Propst.

My why:I asked because We fear liability for that negatively leveraged land under utilized equity asset not to mention the opportunity costs are losing for us.  

@Christian Allen mentioned using Cozy.co for rental management from a rent payment perspective.

Like Josiah already mentioned you would lose a considerable amount of money if you keep the rent below market value. 

@AJ Dhillon In addition to what's already been mentioned.