Neither of our tenants want the added expense of having central AC.  

My personal opinion is that the equity in one property is just as comparable as a less expensive paid property from net worth perspective.  

What exactly is the live in manager free rent but with an expense?

Some folks are willing to give up to 50% of their income for expenses, others try to self-manage. 

Only caveat would be if you were in a high cost of living area where mobiles are very expensive and hard to get.

Our goal is to get enough rental income to cover all of our expenses so that everything we earn from our day jobs is just money we can put towards living the life that we want to live. 

California is probably going to be more expensive though and returns will probably be lower than other parts of the country.

@Michael Newman,I use these sources:current T12 & rent roll (if available)comparable rents from broker's OM packagecomparable rents from neighboring properties (MLS, rentometer.com, umovefree.com, calling to the property)expenses provided by management companies that have similar properties under managementexpenses (ranges) from NAA survey - usually outdated but give a 10000 ft picture and helps establishing some baselines.

Unfortunately, my current employment will not cover the additional properties but with the tenants' rent I could pay for all said expenses.

But I am not for sure which investing strategy is the best one in the progressive & affordable market that I am in (unlike the more expensive California areas).